Periods Of Low Rainfall Research Articles

Implications of climate‐smart agriculture technology adoption on women's productivity and food security in Tanzania

AbstractGender gaps in productivity and food security persist in the face of climate change, necessitating effective strategies for empowering women and reducing their vulnerability. This study examines the gender‐specific impacts of climate‐smart agriculture (CSA) adoption on productivity, food security, and resilience to climate shocks in Tanzania. Using panel data from the World Bank's Tanzanian Living Standard Measurement Survey (LSMS) spanning 2008–2013, we employ a multinomial switching regression model (MSRM) approach to identify the effects of CSA adoption on agricultural outcomes. Our findings reveal that CSA non‐adoption exacerbates the gender gap in yields and food security, favoring men. However, CSA adoption leads to more equitable outcomes, bridging the gender gap and improving productivity and food security for both men and women. Additionally, adopters of CSA techniques exhibit greater resilience to climate shocks, experiencing smaller yield declines during periods of low rainfall. This study contributes to the literature by providing empirical evidence on the gendered impacts of CSA adoption, testing the risk reduction capacity of CSA technologies, and addressing the limited research on Tanzania. The findings emphasize the importance of gender‐responsive CSA policies in promoting agricultural resilience and food security in the face of climate change.

Impact of climate change on permanent lakes in a semiarid region: Southwestern Mediterranean basin (S Spain).

In recent decades, many wetlands in the Mediterranean watershed have dried up. We forecast the impact of climate change on the hydrology of three permanent lakes in a semiarid areo of the southwestern Mediterranean region. To achieve this, we applied daily water balance models to calculate variations in water levels and validated our approach using actual lake level measurements spanning over 20years. To delve into groundwater/lake interactions, we calculated several hydrological indices and compared evaporation with the water level drop during extremely dry periods. After validating the three hydrological models, we applied the RCP 4.5 and RCP 8.5 climate change scenarios. We found Zóñar Lake highly resilient to climate changes because of groundwater contributions, resulting in minimal lake level oscillations even during periods of low rainfall. However, spring management and/or groundwater extractions may affect the lake hydroperiod. The Amarga and Grande lakes have weaker lake/groundwater interactions and show significant water lake level fluctuations, making them more sensitive to climate change. Indeed, our model predict that these lakes will transition into semipermanent or seasonal playa-lakes by mid-21th century. We found that deep and spring and/or groundwater-fed lakes are less vulnerable to climate changes. These results highlight the importance of developing robust hydrogeological models in such water bodies, focusing on the climate changes vulnerability of wetlands in semiarid regions, in order to formulate an integrated strategy for water resources management.

Correlation and Prediction Analysis of Cyanobacteria with Water Environment Data

Objectives : A study was conducted to implement a predictive for cyanobacteria occurrence, a direct indicator of algae presence. Water quality, river environment, and meteorological data were collected and analyzed at six locations along the Nakdong River in Gyeongsangbuk-do and Daegu City. The primary objective was to establish correlations between various environmental factors and validate the utility of predicting algae(cyanobacteria) occurrences.Methods : Cyanobacteria was designated as the dependent variable for correlation analysis. Water quality parameters associated with algal growth, including chlorophyll-a, water temperature, pH, dissolved oxygen(DO), total nitrogen(TN), and total phosphorus(TP), were utilized as key indicators. Additionally, meteorological data such as air temperature, humidity, cloud cover, precipitation, and solar radiation, as well as flow rate and flow quantity, which are indicators of water body stability, were utilized. The collected data were verified and corrected for accuracy before analyzing correlations between cyanobacteria occurrence and the independent variables. Furthermore, cyanobacteria occurrence was predicted using a random forest algorithm, with a linear regression model serving as a baseline for comparison.Results and Discussion : The data presented a normal distribution. Correlation analysis indicated that previous cyanobacteria occurrences had a significant influence on current occurrences. Water temperature showed a positive correlation with cyanobacteria, while DO exhibited a negative correlation. Flow quantity and flow rate were inversely correlated with cyanobacteria cell density. In terms of meteorological data, air pressure negatively correlated with cyanobacteria occurrence, while air temperature showed a positive relationship. Substantial precipitation significantly reduced cyanobacteria concentrations; however, this effect was less pronounced during periods of low rainfall. The linear regression model, with an R2 value of 0.734, demonstrated considerable explanatory power, indicating its effectiveness in accounting for the variability of the dependent variable.Conclusion : The random forest, built on the linear regression model, successfully captured the overall trend of cyanobacteria occurrence when compared with field measurements. The model consistently maintained predictive performance by effectively recognizing complex data patterns, suggesting its potential for reliable prediction of cyanobacteria occurrence trends in aquatic ecosystems.

Land use, hydroclimate and damming influence organic carbon sedimentation in a flood pulse wetland, Malaysia

ABSTRACTWater bodies located in floodplains and tropical forests are known to be important carbon stores, but many are subjected to intensive pressures from damming, land use and climate changes. Sedimentary records preserve long‐term archives for understanding how such changes affect the quantity and quality of carbon stores. We analysed sediment cores from seven sites across a flood‐pulse multi‐basin wetland, Tasik Chini in Peninsular Malaysia (for percentage LOI550, sediment density and spheroidal carbonaceous particles), and conducted more analyses on three 210Pb‐dated cores (X‐ray fluorescence of elements, grain size analysis, carbon isotopes, C/N ratios, carotenoid pigments) to gain an understanding of the drivers of organic carbon accumulation rates (OCARs) since 1860 ce. The median OCAR of 85 g m−2 a−1 for the basin since 1945 ce was higher than in other floodplain and temperate lakes and in line with other tropical forest lakes. However, we found evidence for different mechanisms of OC deposition across the basin. In ‘autochthonous mode’, the site with minimal local land disturbance had lowest OCARs and OC was derived mainly from autochthonous production, which rose slightly around 1940 ce when regional land disturbance increased nutrient influx to the basin. The site with the most long‐term and intensive land disturbance through forest removal (1940s) and then conversion to rubber and oil palm farming (1980s) functioned mainly in ‘allochthonous mode’; that is, increases in OCARs after 1940 ce were driven by deposition of soil‐derived OC. The highest OCARs were in the basin that was converted to oil palm after the 1980s and had increased iron mining activity in the 2000s; because this site was located distal from the flood pulse and became increasingly hydrologically disconnected after a low rainfall period in the 1970s, the lake responded strongly in ‘autochthonous mode’, through encroachment of fringing swamp, the spread of benthic algae and macrophytes, and efficient sediment retention. Weir installation in 1995 ce raised water levels and increased lentic conditions, promoting autochthonous OC production and sedimentation across all basins. The long‐term fate of this more recently deposited OC remains uncertain because it is more labile. Overall Tasik Chini has responded strongly to land use changes since at least the 1940s, earlier than anticipated in this region of Southeast Asia, and the sedimentary proxies indicate large changes in the ecosystem function and capacity for C storage over the past ca. 80 years. Most of these shifts have increased OC accumulation by strengthening autochthonous production or allochthonous OC fluxes, but the implications for other aspects of the C cycle, including catchment soil C loss and greenhouse gas production, need to be accounted for when evaluating the overall impacts of land and hydrological disruption.

Short-Term Effects of Incorporation Depth of Straw Combined with Manure During the Fallow Season on Maize Production, Water Efficiency, and Nutrient Utilization in Rainfed Regions

Diminishing soil fertility and crop productivity due to traditional intensive cultivation has prompted the use of straw and manure to improve soil health in Northeast China. However, few comparative studies have explored the influence of varying straw and manure incorporation depths on crop growth. A field experiment in the rainfed black soil regions of Gongzhuling and Keshan assessed the effects of deep (30 cm) and shallow (15 cm) incorporations of straw and manure on soil fertility, maize root growth, and maize productivity. Deep incorporations, via subsoiling tillage (DST) and deep-plow (DDT) tillage, enhanced soil water storage of 30–100 cm soil layer during periods of low rainfall, improved the availability of nutrients (nitrogen, phosphorus, and potassium) and soil organic matter content, especially in deeper soil, compared to shallow incorporation using rotary tillage (SRT). Both DST and DDT induced a larger rooting depth and a higher fine root (diameter class 0–0.5 mm) length density by 31.0% and 28.9%, respectively, accompanied by reduced root turnover. Furthermore, the sub-surface foraging strategies of roots under the DST and DDT treatments boosted the total nitrogen, phosphorus, and potassium uptake (6.5–17.9%) and achieved a higher dry mass accumulation during the later growth period, thus leading to notable improvements in the 100-kernel weight and yield (16.1–19.7%) and enhancing water- and nutrient-use efficiencies by 2.5–20.5%. Overall, compared to shallow incorporation, deep incorporation of straw and manure significantly enhances root growth and spatial distribution of soil water and nutrients, which has great potential for increasing maize yield in rainfed agricultural areas.

Culture, climate, and landscape shape the savanna and wetland mosaic of the Bolivian Amazon

Environmental archeology of the Amazon has conventionally focused on terrestrial spaces, investigating crop domestication and production, agroforestry and anthropogenic soils. Aquatic environments, however, have been given less attention by archeologists and paleoenvironmental scientists alike. The Llanos de Mojos, a 135,000 km2 basin of the Amazon and mosaic landscape of savannas, wetlands and forests, has long been recognized for its archeological record. A variety of anthropogenic earthworks across the region show significant landscape modifications from Pre-Columbian times used for transportation, resource production and control of floodwaters. Here, we investigate the use and management of wetlands, and their interaction in the wider Mojos mosaic landscape, by integrating extensive archeological, paleoenvironmental and GIS datasets. We demonstrate that past human modifications of the landscape enabled the creation of complex wetland-terrestrial system of resource production, in which wetlands were managed, complementary to terrestrial crop production and agroforestry. Across short distances (40 km), land use strategies were heterogeneous despite being connected in time and space. Additionally, mixed wetland-terrestrial resource production was relatively stable during periods of lower rainfall from 1200–1500 CE, implying that this strategy provided flexibility under conditions of variable climate. The wetlands of the Llanos de Mojos are the result of millennia of human intervention and recognition of this deep heritage is required to make informed management and conservation decisions to ensure the future of this culturally and biologically diverse region.

Deciphering the importance of morphological aspects in drought tolerance in eucalyptus progenies

Water limitation is one of the factors that most impact plant growth and productivity, especially for Eucalyptus. For commercial eucalyptus plantations to develop properly, it is essential to select clones with drought-tolerant characteristics, especially in areas with low rainfall and well-defined dry periods. Accordingly, climate change, mainly related to increases in mean annual temperature, can lead to a more severe water deficit and ultimately harm plant development. Thus, the identification of indicators related to climatic variables enables the selection of clones with drought tolerance characteristics. Here, we used 27 families of eucalyptus progenies from crosses of plants with previously selected characteristics associated with drought tolerance, which were planted in a region characterized by high water deficiency. Sample harvesting was performed at 6, 18, and 30 months after planting, at the end of natural drought cycles. Meteorological data coupled with physiological analyses allow the early selection of Eucalyptus clones that are better able to tolerate recurrent drought events. Specific leaf area (SLA), leaf area (LA), length (L), width (W), and leaf water potential (ΨL) were analyzed. The parameters SLA, LA, and ΨL proved to be good bioindicators of Eucalyptus drought tolerance. Specific clones and progenies (e.g., GG2673, VM1, GG1923, GG1980, GG3389XGG4302, GG918XVS62, AEC2034xLR831, I3000XVM1, VM4XCAM, and VM1xVM4) were characterized by physiological adjustments and showed higher average annual volumetric increment (IMAvol) values and were assumed as genetic materials with potential drought tolerance.

Impact of forest fires in bromo national park: Analysis of the environment and recovery efforts

Background: Forest fires represent natural disasters that often stem from environmental conditions, including events like El Niño or extreme climatic situations. Rainfall, a crucial factor, plays a role in influencing extreme climate occurrences. In Indonesia, human activities predominantly contribute to forest fires, exacerbated by extreme climatic conditions. Areas with high potential for forest fires encompass conservation zones closely linked to human activities. An illustrative example is the Bromo Tengger Semeru National Park (TNBTS), which serves both as a conservation and tourist area. The presence of human tourists or visitors in these conservation zones creates conditions conducive to forest fires, particularly when supported by extreme climatic conditions. Method: This study used field observation methods, satellite data analysis, and interviews with authorities and environmental experts. The data collected included the area affected, the plant types, and the environmental conditions after the fire. Findings: TNBTS experiences a specific rainfall pattern, with the lowest precipitation observed in May-Jun-Jul-Aug-Sept and the highest in Nov-Dec-Jan-Feb-Mar. During periods of low rainfall, TNBTS becomes susceptible to fires, necessitating preventative measures in the month leading up to the dry season. Initiating preventative actions at the onset of the dry season, notably in May, is crucial for controlling forest fires. Analyzing hotspot data of fire incidents from 2001 to 2020 reveals peak occurrences among other nationalities in 2001, 2014, and 2019. Identification based on data indicates that not all hotspots signify fire incidents; some result from heat emanating from Mount Semeru's crater at the TNBTS location. Conclusion: This article concludes the importance of cooperation between authorities, environmental organizations, and communities in forest fire prevention and recovery efforts in Bromo National Park. It emphasizes the need for increased preventive and responsive measures to protect similar conservation areas in the future. Novelty/Originality in this article: This study also offers a new perspective in the interpretation of hotspot data by distinguishing between forest fires and volcanic activity and identifying May as a critical period for initiating preventive action analysis based on long-term rainfall patterns.

Characterization and Seasonal Dynamics of Tick Populations in Dairy Cattle Production Systems of Northwestern Colombian Amazon.

Cattle ticks are a significant health concern in tropical livestock production due to their hematophagous behavior and potential as vectors for human and animal pathogens. In this study, we investigated the tick population present in dairy cattle production, calves, and grazing areas of livestock systems in the northwestern Colombian Amazon. Identification was based on taxonomic keys and molecular markers. Phylogenetic relationships were established using mitochondrial COX1 and 16S genes. Population structure analysis was performed considering age, racial type (B. indicus vs. B. taurus), and the influence of environmental factors and the geomorphological landscape on tick population dynamics. Our findings revealed the presence of a single tick species, with a unique haplotype identified for each mitochondrial gene assessed. Phylogenetic analysis classified the found species within Clade A of the Rhipicephalus microplus complex. Ticks were more prevalent during periods of low rainfall and high temperature, and B. taurus cows exhibited the highest tick abundance. Thus, these results provide insights into the population characteristics and distribution of the tick species present in dairy cattle production systems in the northwestern part of the Colombian Amazon. This information is fundamental for developing targeted strategies based on seasonal variation and host characteristics to mitigate tick infestation severity in the region.

Wide Riparian Zones Inhibited Trace Element Loss in Mining Wastelands by Reducing Surface Runoff and Trace Elements in Sediment.

The diffusion of trace elements in mining wastelands has attracted widespread attention in recent years. Vegetation restoration is an effective measure for controlling the surface migration of trace elements. However, there is no field evidence of the effective riparian zone width in mining wastelands. Three widths (5 m, 7.5 m, and 10 m) of Rhododendron simsii/Lolium perenne L. riparian zones were constructed in lead-zinc mining wastelands to investigate the loss of soil, cadmium (Cd), copper (Cu), arsenic (As), lead (Pb), and zinc (Zn). Asbestos tiles were used to cut off connections between adjacent plots to avoid hydrological interference. Plastic pipes and containers were used to collect runoff water. Results showed that more than 90% of trace elements were lost in sediment during low coverage and heavy rainfall periods. Compared with the 5 m riparian zone, the total trace element loss was reduced by 69-85% during the whole observation period in the 10 m riparian zone and by 86-99% during heavy rain periods in the 10 m riparian zone, which was due to reduction in runoff and concentrations of sediment and trace elements in the 10 m riparian zone. Indirect negative effects of riparian zone width on trace element loss through runoff and sediment concentration were found. These results indicated that the wide riparian zone promoted water infiltration, filtered soil particles, and reduced soil erosion and trace element loss. Riparian zones can be used as environmental management measures after mining areas are closed to reduce the spread of environmental risks in mining wastelands, although the long-term effects remain to be determined.

Determining Water Use Patterns for the Betula platyphylla in the Southern Greater Khingan Mountains and Its Adaptation to Drought

Due to global climate change, seasonal droughts have intensified and become more frequent in certain semi-arid regions, and plants often adjust their water uptake depths to adapt to shifting environmental conditions. The southern Greater Khingan Mountains have a large natural secondary forest area and act as an important ecological barrier. This study focused on examining the water use patterns of the primary plant species, Betula platyphylla, within the natural secondary forest of the southern Greater Khingan Mountains. The investigation utilized oxygen stable isotope techniques and covered a timeframe spanning from July 2019 to September 2020. The findings indicate that the adaptable water utilization strategies and rapid response to precipitation could facilitate plants fully utilizing water from all depths, thereby enabling them to better adapt to arid environments. When the rainfall was low (390.4 mm in the growing season of 2019), the developed shallow roots quickly absorbed shallow soil water (0–20 cm, with a utilization ratio of 40.4% for the entire root depth), but when the rainfall increased (501.5 mm in the growing season of 2020), Betula platyphylla gradually transitioned to extracting soil water from deeper soil layers (40–60 cm) and deepened its root system (with a utilization ratio of 39.4%), indicating its adaptability to semi-arid environments. Therefore, the flexible water use strategy of Betula platyphylla in the same habitat may give it a competitive advantage during low rainfall periods. The findings are important for the protection of natural forests and water management in the southern Greater Khingan Mountains.

EFFECT OF DIFFERENT SPATIAL ARRANGEMENTS OF Jatropha curcas L. ON FOOD CROPS

The objective of this study was to assess, during three years, the spatial arrangement that will enhance the morpho-productive development of Jatropha curcas L. in association systems with staple crops. It was hypothesized that the association of crops is a factor that determines the behavior of the species and the development of agroenergetic farms, considering rainy and low rainfall periods. A quasi-experimental design was used, and four treatments were tested: 1) J. curcas (Jc) in monoculture; 2) 50 % of the area with Jc and 50 % planted with food crops in rotation (CA); 3) Jc intercropped with CA; and 4) area planted with CA. A principal component statistical analysis was performed with the variables fruit yield and associated crop yield using 95 % confidence intervals from a Student’s t-test. The number of bunches and total fruit and seeds harvested from Jc were shown to be the most important and had a positive correlation for the first component in each period. As for fruit yield, the highest values were achieved in monoculture. Although high yields were not attained in CA, the relationship is regarded favorable since the use of polycultures is viable, fundamentally in the arrangement of 50 % Jc + 50 % CA, being positive the biological efficiency given by the diversification and the best equivalent land use.

Ridge with no-tillage facilitates microbial N2 fixation associated with methane oxidation in rice soil

Aerobic methane-oxidizing bacteria (MOB) play a crucial role in mitigating the greenhouse gas methane emission, particularly prevalent in flooded wetlands. The implementation of ridge with no-tillage practices within a rice-rape rotation system proves effective in overcoming the restrictive redox conditions associated with waterlogging. This approach enhances capillary water availability from furrows, especially during periods of low rainfall, thereby supporting plant growth on the ridges. However, the microbe-mediated accumulation of soil organic carbon and nitrogen remains insufficiently understood under this agricultural practice, particularly concerning methane oxidation, which holds ecological and agricultural significance in the rice fields. In this study, the ridge and ditch soils from a 28-year-old ridge with no-tillage rice field experiment were utilized for incubation with 13C-CH4 and 15NN2 to estimate the methane-oxidizing and N2-fixing potentials. Our findings reveal a significantly higher net production of fresh soil organic carbon in the ridge compared to the ditch soil during methane oxidation, with values of 626 and 543 μg 13C g−1 dry weight soil, respectively. Additionally, the fixed 15N exhibited a twofold increase in the ridge soil (14.1 μg 15N g−1 dry weight soil) compared to the ditch soil. Interestingly, the result of DNA-based stable isotope probing indicated no significant differences in active MOB and N2 fixers between ridge and ditch soils. Both Methylocystis-like type II and Methylosarcina/Methylomonas-like type I MOB catalyzed methane into organic biomass carbon pools. Soil N2-fixing activity was associated with the 15N-labeling of methane oxidizers and non-MOB, such as methanol oxidizers (Hyphomicrobium) and conventional N2 fixers (Burkholderia). Methane oxidation also fostered microbial interactions, as evidenced by co-occurrence patterns. These results underscore the dual role of microbial methane oxidation – not only as a recognized sink for the potent greenhouse gas methane but also as a source of soil organic carbon and bioavailable nitrogen. This emphasizes the pivotal role of microbial methane metabolism in contributing to soil carbon and nitrogen accumulation in ridge with no-tillage systems.

Development of a drought-resilient water supply from dolomitized limestones of the Irish Midlands

A hydrogeological investigation is presented that focused on the development of a drought-resilient groundwater supply for a town (Carlow) in the Irish Midlands. The combination of thick overlying glacial deposits and Carboniferous limestones of low primary permeability posed a challenge to identifying a groundwater source. The source exploration strategy comprised surface geophysics and follow-on pilot well drilling to identify zones of high (secondary) permeability in bedrock. The study identified a previously unrecorded large ( c . 3.5 km long) and deep infilled karst feature that possibly extends 2 km further to a nearby area of known Neogene-aged karst infill. Separately, the investigation revealed new areas of dolomitized limestone, suitable for water supply development, where two production wells were constructed. A programme of pumping tests showed that dolomitized limestone areas exhibited low-nitrate groundwater quality, relatively high transmissivity and sustained recharge boundaries (leakage from a nearby riverbed). Analysis of data from the operational stage provided further insights into recharge behaviour, and showed that groundwater levels are resilient during droughts at current abstraction rates. The analysis concluded that the wellfield could sustain higher abstraction volumes, even through extended periods of low effective rainfall. Thematic collection: This article is part of the Climate change and resilience in Engineering Geology and Hydrogeology collection available at: https://www.lyellcollection.org/topic/collections/climate-change-and-resilience-in-engineering-geology-and-hydrogeology

A sequence of multiyear wet and dry periods provides opportunities for grass recovery and state change reversals

AbstractMultiyear periods (≥4 years) of extreme rainfall are increasing in frequency as climate continues to change, yet there is little understanding of how rainfall amount and heterogeneity in biophysical properties affect state changes in a sequence of wet and dry periods. Our objective was to examine the importance of rainfall periods, their legacies, and vegetation and soil properties to either the persistence of woody plants or a shift toward perennial grass dominance and a state reversal. We examined a 28‐year record of rainfall consisting of a sequence of multiyear periods (average, dry, wet, dry, average) for four ecosystem types in the Jornada Basin. We analyzed relationships between above ground net primary production (ANPP) and rainfall for three plant functional groups that characterize alternative states (perennial grasses, other herbaceous plants, dominant shrubs). A multimodel comparison was used to determine the relative importance of rainfall, soil, and vegetation properties. For perennial grasses, the greatest mean ANPP in mesquite‐ and tarbush‐dominated shrublands occurred in the wet period and in the dry period following the wet period in grasslands. Legacy effects in grasslands were asymmetric, where the lowest production was found in a dry period following an average period, and the greatest production occurred in a dry period following a wet period. For other herbaceous plants, in contrast, the greatest ANPP occurred in the wet period. Mesquite was the only dominant shrub species with a significant positive response in the wet period. Rainfall amount was a poor predictor of ANPP for each functional group when data from all periods were combined. Initial herbaceous biomass at the plant scale, patch‐scale biomass, and soil texture at the landscape scale improved the predictive relationships of ANPP compared with rainfall alone. Under future climate, perennial grass production is expected to benefit the most from wet periods compared with other functional groups with continued high grass production in subsequent dry periods that can shift (desertified) shrublands toward grasslands. The continued dominance by shrubs will depend on the effects that rainfall has on perennial grasses and the sequence of high‐ and low‐rainfall periods rather than the direct effects of rainfall on shrub production.

Assessing Terrestrial Water Storage Variations in Southern Spain Using Rainfall Estimates and GRACE Data

This paper investigates the relationship between rainfall, groundwater and Gravity Recovery and Climate Experiment (GRACE) data to generate regional-scale estimates of terrestrial water storage variations in the Andalucía region of southern Spain. These estimates can provide information on groundwater depletion (caused by periods of low rainfall or droughts) and groundwater recovery. The spatial distribution of groundwater bodies in southern Spain is complex and current in situ groundwater monitoring methods are deficient, particularly in terms of obtaining representative samples and in implementing and maintaining groundwater monitoring networks. The alternative approach proposed here is to investigate the relationship between precipitation time series and changes in the terrestrial water storage estimated from GRACE observations. The results were validated against the estimated fluctuation in regional groundwater. The maximum correlation between the mean groundwater level and the GRACE observations is 0.69 and this occurs at a lag of one month because the variation in gravity is immediate, but rainfall water requires around one month to travel across the vadose zone before it reaches the groundwater table. Using graphical methods of accumulated deviations from the mean, we show that, in general, groundwater storage follows the smooth, multi-year trends of terrestrial water storage but with less short-term trends; the same is true of rainfall, for which the local trends are more pronounced. There is hysteresis-like behaviour in the variations in terrestrial water storage and in the variations of groundwater. In practical terms, this study shows that, despite the abnormal dryness of the Iberian Peninsula during the 2004–2010 drought, the depleted groundwater storage in Andalucía recovered almost to its pre-drought level by 2016. In addition, groundwater storage and terrestrial water storage show very similar trends but with a delay in the groundwater trend.

Responses of soil CO2 efflux and microbial activity to water deficit under conventional and adaptation technology

Frequent periods of low rainfall accompanying climate change are expected to affect many aspects of agricultural production and greenhouse gas emissions. In this work, we conducted field experiments on soil CO2 efflux and soil microbial activity using two precipitation treatments and two crop management technologies. While the control treatment was exposed to natural precipitation, the reduced water availability was induced during the early stages of crop growth using rain-exclusion shelters within the water deficit treatment. We aimed to test the difference in the response to water deficit between two management technologies: conventional tillage (CT - ploughed without cover crops) and adaptation technology (AT - no-till with species rich cover crops). After a month of simulated water deficit, the soil CO2 efflux under a regime of adaptation technology was essentially the same as that under the conventional technology, and the decrease in soil CO2 efflux ranged between 22 % and 55 %. The water deficit had a technology-specific effect on microbes. While no effect on the microbial carbon under CT was observed, the water deficit decreased Cmic under AT. In contrast, the opposite pattern was observed for DHA. When a normal soil water regime was restored, CO2 efflux recovered rapidly while recovery of microbial biomass and dehydrogenase activity was more variable. Generally, the soil microbial biomass and activity recovered better under AT. The results show that while the reduction in Rs during water deficit and its recovery after the restoration of the ambient precipitation regime were not affected by the technology, the response of microbial biomass and activity to water deficit depended on the technology with better recovery under AT.

A Comparison of Different Stomatal Density Phenotypes of Hordeum vulgare under Varied Watering Regimes Reveals Superior Genotypes with Enhanced Drought Tolerance.

Enhancing the water-use efficiency (WUE) of barley cultivars may safeguard yield deficits during periods of low rainfall. Reduced stomatal density is linked to enhanced WUE, leading to improved drought resistance across plant genera. In this study, 10 barley varieties exhibiting a range of stomatal density phenotypes were grown under differing soil water contents to determine whether stomatal density influences the capacity of genotypes to resist low water availability. The low-stomatal-density genotype Hindmarsh showed the least impact on biomass production during early development, with a 37.13% decrease in dry biomass during drought treatment. Low-stomatal-density genotypes additionally outcompeted high-stomatal-density genotypes under water-deprivation conditions during the reproductive phase of development, exhibiting 19.35% greater wilting resistance and generating 54.62% more heads relative to high-stomatal-density genotypes (p < 0.05). Finally, a correlation analysis revealed a strong negative linear relationship between stomatal density and the traits of head number (r = -0.71) and the number of days until wilting symptoms (r = -0.67) (p < 0.05). The combined results indicate that low-stomatal-density genotypes show promising attributes for high WUE, revealing novel barley varieties that may be useful to future breed improvement for drought tolerance.

‘The Long, Continued Dry’

Droughts are a canonical feature of Australian history and climate, and Australia’s paleoclimate and colonial past is dotted with extended periods of low rainfall. The Federation Drought was one such period. The result of a series of El Niño events, it parched much of Australia between 1895 and 1903 and remains one of the most significant and prolonged periods of rainfall deficiency since European colonisation. It also coincided with, and fuelled, a substantial increase in press coverage of the weather. In this article we examine reportage of the Federation Drought through two newspapers from the Victorian city of Bendigo: The Bendigo Advertiser and The Bendigo Independent. We identify themes that have persisted in drought coverage to the present day, highlighting the role the press has played in shaping how communities and policy makers have understood and managed the extremities of Australia’s climate. We also offer insights into the evolution of current drought reportage and the perspectives it enables or silences.

Microplastic abundance, distribution, and diversity in water and sediments along a subtropical river system.

Microplastic pollution in aquatic environments has been a ubiquitous concern in recent years, owing to their rapid production combined with poor waste management practices. However, information on freshwater microplastics in the Global South is still scarce, despite growing research on freshwater microplastics in recent years, particularly within the Global North. To help address this knowledge gap, we studied water and sediment microplastic dynamics along a subtropical river system, i.e. Crocodile River around the Nelspruit City area (South Africa), across three different seasons (i.e. cool-dry, hot-dry, hot-wet) using a combination of diversity indices and multivariate analyses. Microplastics were more abundant during the cool-dry season in the surface water samples (mean 1058 particles m-3) and high during the hot-dry season (mean 568 particles kg-1 dwt) in the sediment samples. The hot-wet season had a low particle density in both surface water (mean 625 particles m-3) and sediments (mean 86 particles kg-1 dwt) samples. Microplastic shapes were dominated by fibres and fragments, with the colour scheme dominated by transparent, blue, and black. The abundance of microplastics was positively correlated with pH and resistivity, and negatively with river flow. Wastewater was attributed as a primary source of microplastics, particularly because of the observed dominant fibre microplastics, usually released during laundry. Our results suggest that Crocodile River and its tributaries are temporary sinks of microplastics during periods of low rainfall. Implications of this pollution are far-reaching, including effects on residents who are dependent on the Crocodile River as a source of drinking water and aquatic biota which may be exposed to these pollutants.