Dry Areas Research Articles

ANÁLISE ESPACIAL E TEMPORAL DE EVENTOS DE SECAS NA REGIÃO HIDROGRÁFICA ALTO RIO PARANÁ DE 1990 A 2020

The Paraná River Hydrographic Region is of great socioeconomic relevance for Brazil. Therefore, due to the history of droughts in the region, the aims of the current study were to assess rainfall spatial and temporal variability, as well as to analyze drought features based on using the Normalized Percentage Index (NPI) to contribute to water management processes in Upper Paraná River (UPR). The study area encompasses 14 Planning and Management Units, distributed in Goiás, Mato Grosso do Sul, Minas Gerais and São Paulo states. Climate data were obtained from the National Hydrometeorological Network database. A geostatistical analysis of rainfall was carried out, based on the annual series of 408 stations, and subsequently the calculation of NPI for classifying the droughts severity. All periods analyzed (1990-2020) showed spatial dependence (moderate to high), allowing the elaboration of droughts maps. The dry and rainy periods and areas did not indicate direct influence of El Niño-Southern Oscillation (ENSO). Mato Grosso do Sul and São Paulo units were the main contributors to the identified droughts. The data showed that 2010-2020 was the driest decade of the period, with a greater contribution from the 2019/2020 period, where droughts exceeded 60% of the area for two consecutive years, an event never identified in the last 3 decades. The NPI curves referring to “initial drought” and “mild” allowed verifying years of water crisis when their summed percentages reached at least 50% of the region. The methodology used is versatile, allowing its use in any watershed. Keywords: Rains. Water management. NPI. Kriging.

Spatial-Temporal Analysis of Land Cover Change and Oil Palm Expansion in Gunung Mas

Abstract: The area of oil palm plantations in Indonesia has increased over time. The growth of oil palm plantations even exceeds the percentage of the area of paddy fields, especially in Gunung Mas Regency. This phenomenon is accompanied by the implementation of "Regional Regulation No. 1 of 2020 concerning Land Fire Control". The regulation aims to prevent land fires due to human activities. However, local people believe that burning can increase land productivity. As a result, many people convert their land to plant oil palm, because it is considered to guarantee economic improvement compared to paddy fields. Remote sensing satellite imagery is the basis and main source in the analysis. With spatio-temporal analysis, mapping of land use changes in a certain period of time and its relationship with the distribution of agricultural wet and dry areas. As a result, the proportion of palm oil land in Gunung Mas Regency is higher than the proportion of paddy fields. If oil palm expansion continues in the future, agricultural drought could become more widespread. Keywords: Expansion of oil palm, Land use change, Paddy Fields, Remote sensing, Spatio-Temporal Analysis

Growing Vigorous Potato Seedlings in Plug Trays

AbstractRaising vigorous and healthy potato seedlings from hybrid true potato seeds (TPS) under nursery conditions is critical for ease of field transplanting and seedling crop establishment as well as for a productive seed or ware crop. The use of plugs in seedling production systems is an important technique utilised to ease transplanting of seedlings and refine seedling production in seedling nurseries. While holding multiple advantages over other transplant production systems, multiple factors still influence the success of seedling production in plug trays. In this study, we explore the effects of substrate properties, type and volume; watering intervals; and nitrogen (N) and phosphorus (P) levels in nutrient solution on seedling vigour attributes in potato seedlings grown in plug trays under climate room conditions. The choice of substrate strongly influenced seedling attributes with more favourable performance in substrates with higher water holding capacity. Increasing plug volume also enhanced seedling attributes including dry biomass, leaf area and root to shoot ratios such that seedling performance was best in plug volumes > 22.5 cm3. A watering schedule with a high frequency was more favourable considering that longer intervals between watering events led to significant declines in seedling attributes. While the effects of increased P in solution were not conclusive, depending on genotype, increasing N in solution led to enhanced seedling attributes, with a nutrient sufficiency met at 200 mg L−1 N in solution. These findings further contribute to the current knowledge on factors influencing success in seedling production of potato seedlings developed from hybrid true potato seeds.

Hydrographic and hydrochemical characteristics of selected groundwater outflows in desert and semi-desert areas

The presence of natural groundwater outflows depends on many factors, such as lithology, geological structure, and climate. Areas with particularly poor crenological recognition are arid and semi-arid regions, primarily due to rarity of groundwater outflows in these locations. The article presents the hydrographic and hydrochemical characteristics of selected groundwater outflows in arid and semi-arid areas. In addition to hydrographic mapping, basic physical parameters of water were measured in selected springs, such as temperature (T, °C), electrolytic conductivity (EC, μS∙cm–1), and reaction (pH, –). Laboratory analyses determined the major cations and anions in water: Ca2+, Mg2+, Na+, K+, NH4+, SO42−, Cl−, NO3−, Br−, PO43−,. The analyses were performed using an ion chromatograph Metrohm 850 Professional IC. Twenty-four natural groundwater outflows in South America, Africa, and Asia were selected for research. It was found that the vast majority of outflows are transit sources. Their supply area may be far from discharge points. The supply source is rainwater or meltwater from high mountain massifs. Other types of outflow are springs of alluvial fans and braided rivers. They are fed by waters from glacial rivers, which infiltrate alluvial deposits and flow back to the surface. Hydrochemical analysis has shown that the physicochemical properties of water in dry areas vary significantly. Still in the hydrochemical type, there is a predominance of sulphate, chloride, and sodium ions. This distinguishes the spring waters from these areas in temperate latitudes, which are dominated by bicarbonate and calcium ions.

Impact of climatic trends on the water demand and irrigation planning for annual crops in the São Francisco River basin, Brazil

This study evaluated the spatial distribution of precipitation (P) and Peman-Monteith reference ET (ETo) in Brazil's São Francisco River basin (1961–2022). The analysis included Mann-Kendall trend tests and future IPCC projections on P and ETo to assess the need for supplemental irrigation (SI) of maize crop over twelve hypothetical growing seasons. The average annual P in the basin was 1300 mm year−1, decreasing from the Upper to the Lower section. Annual ETo averaged 1670 mm year−1, with higher depths in the Middle and Lower-middle sections. Trends for both P and ETo were significant(p < 0.05) in 58% of the basin. The overall trend magnitude in P was positive (average of about 0.5 mm year−2). Trend was decreasing in 56% of the sites (3.2 mm year−2) and increasing in 44% of them (5.3 mm year−2). For ETo, the overall trend was also positive (average of 3.0 mm year−2), with increasing trend in 79% of the sites (4.6 mm year−2) and a decreasing trend of 3.8 mm year−2 in 21% of the area. The need of SI varied both over the year with peaks in the May–August period and over the basin with higher depths in the Middle and Lower-middle sections. Large SI values (>800 mm) were associated with the dry season and areas with persistent trends in decreasing P and increasing ETo. Future IPCC projections indicate increased SI depths in most of the basin by 2081–2100, with the Middle and Lower-middle sections facing potentially unsustainable level for crop production.

How biochar curbs the negative impacts of plastic mulching on soil enzymes and microorganisms while elevating crop yields in ridge-furrow systems

Ridge-furrow tillage is an important tillage and yield enhancement method used in dry farming areas; however, the spatial characteristics of the soil microenvironment under ridge-furrow tillage and the response of crop yields to mulching and biochar addition are not known. In this study, we conducted a three-year field experiment in which mulch and biochar, alone or combined, were introduced into ridge-furrow tillage system to explore their interactive effects on soil enzyme activities, bacterial communities, functional genes, and crop yields. The findings reveal significant spatial differences in soil physicochemical composition, enzyme activity, microbial communities, and functional genes under ridge-furrow tillage, which are further exacerbated by the addition of mulching and biochar. Under the premise of ridge-furrow tillage, both mulching and biochar addition reduce the α diversity of bacterial communities. Mulching simplifies the bacterial network, while biochar addition has the opposite effect. Mulching and biochar addition increase the relative abundance of carbon, nitrogen, and phosphorus functional genes and accelerate nutrient cycling, especially on the ridges. Mulching significantly improves crop yield but is detrimental to alkaline phosphatase activity and the abundance of the gene function. The addition of biochar mitigates the harm of mulching and further increases alfalfa yield. These findings not only provide scientific support for optimizing ridge-furrow tillage but also deepen our comprehensive understanding of the soil biochemical environment after the addition of mulching and biochar, further revealing their positive effects on yield formation.

Mitigating Salinity Stress in Cotton (Gossypium hirsutum L.) with K-humate and Iron Oxide Nanoparticles

Salinity stress poses a major challenge to plant growth and development, causing problems like osmotic stress, ion toxicity, and nutrient imbalances. These issues lead to reduced photosynthesis and early aging of plants. In this study, we explored the potential of potassium humate (Kh) and iron oxide nanoparticles (Fe (II,III) oxide-NPs) to help cotton plants (Gossypium hirsitum L.) cope with saline conditions. We examined various growth parameters such as plant height, leaf number, fresh and dry weights of leaves and roots, leaf area, chlorophyll content (SPAD values), and relative water content (RWC). Our findings showed that salinity stress significantly decreased plant height, leaf number, fresh leaf weight, dry leaf weight, leaf area, and RWC. However, the application of Fe (II,III) oxide-NPs and Kh helped mitigate these negative effects. Notably, the combination of Fe (II,III) oxide-NPs and Kh resulted in the highest plant height under saline conditions. Kh alone was particularly effective in increasing leaf number and fresh leaf weight, even under stress. In conclusion, both Fe (II,III) oxide NPs and Kh proved to be effective in enhancing cotton plant resilience to salinity stress, highlighting their potential use in sustainable agriculture in saline and arid regions. These insights can help develop strategies to improve plant growth and yield under challenging environmental conditions.

Growth, Evapotranspiration, Gas Exchange and Chl a Fluorescence of Ipê-Rosa Seedlings at Different Levels of Water Replacement.

In general, young plants in the establishment phase demonstrate sensitivity to changes in environmental conditions, especially regarding water availability. The effects of the seasonality of biophysical processes on plant physiology can trigger differential responses, even within the same region, making it necessary to conduct studies that characterize the physiological performance of the species at different spatial and temporal scales, making it possible to understand their needs and growth limits under water stress conditions. This paper aimed to evaluate the growth, gas exchange and Chl a fluorescence in ipê-rosa seedlings subjected to levels of water replacement (LWRs) of 100, 75, 50 and 25% in a greenhouse. The morphometric variables of plant height, diameter at stem height, numbers of leaves and leaflets, root length and volume, plant dry mass and leaf area were evaluated. The potential evapotranspiration of seedlings (ETc) was obtained using direct weighing, considering the water replacement of 100% of the mass variation between subsequent days as a reference; the cultivation coefficients (kc) were obtained using the ratio between ETc and the reference evapotranspiration (ETo) obtained by the Penman-Monteith FAO-56 method. Biomass and evapotranspiration data were combined to determine water sensitivity. Diurnal fluxes of gas exchange (net photosynthesis rate, transpiration rate, stomatal conductance, internal and atmospheric carbon ratio, water use efficiency and leaf temperature) and Chl a fluorescence (Fv/Fm, ΦPSII, ETR, Fv'/Fm', NPQ and qL) were evaluated. Water restriction caused reductions of 90.9 and 84.7% in the increase in height and diameter of seedlings subjected to 25% water replacement when compared to seedlings with 100% water replacement. In comparison, biomass accumulation was reduced by 96.9%. The kc values increased throughout the seedling production cycle, ranging from 0.59 to 2.86. Maximum water sensitivity occurred at 50% water replacement, with Ky = 1.62. Maximum carbon assimilation rates occurred in the morning, ranging from 6.11 to 12.50 µmol m-2 s-1. Ipê-rosa seedlings regulate the physiology of growth, gas exchange and Chl a fluorescence depending on the amount of water available, and only 25% of the water replacement in the substrate allows the seedlings to survive.

Reptile Diversity Patterns Under Climate and Land Use Change Scenarios in a Subtropical Montane Landscape in Mexico

ABSTRACTAimMountainous regions are rich in reptile biodiversity but face threats from climate and land use changes. Understanding how these factors affect reptile diversity in these regions can highlight key conservation hotspots that require effective conservation actions. Here, we explored reptile taxonomic and functional diversity patterns along the Sierra Madre del Sur region in southeast Mexico, and potential changes in future years caused by different climate and land use change scenarios.LocationSierra Madre del Sur, México.TaxonReptiles.MethodsWe used species distribution models and information on species traits to estimate taxonomic and functional diversity throughout the Sierra Madre del Sur (SMS) region under current and future climate and land use change scenarios.ResultsGreater taxonomic and functional diversity was observed in both temperate and tropical forests. Taxonomic diversity was higher in more drier areas at high elevations while higher functional diversity was observed in wetter areas at intermediate‐to‐high elevations. Lower diversity for both dimensions was associated with anthropic land uses. In future scenarios, both dimensions of diversity are expected to increase in temperate forest in highlands of central Oaxaca and decrease in the southcentral portion of the SMS, particularly for the worst scenarios due to increased deforestation rates.Main ConclusionsHigher taxonomic diversity in more drier areas at high elevations could be due to historical and evolutionary factors, while higher functional diversity in wetter areas at intermediate‐to‐high elevations may be explained by a higher environmental heterogeneity in forests within these conditions. Larger diversity losses in the southcentral portion of the SMS are probably due to larger predicted deforestation rates in those areas. Our results are valuable not just for informing conservation actions, such as the creation of protected natural areas but also to understand the underlying processes behind the patterns of reptile diversity.

Warming and disturbances affect Arctic-boreal vegetation resilience across northwestern North America.

Rapid warming and increasing disturbances in high-latitude regions have caused extensive vegetation shifts and uncertainty in future carbon budgets. Better predictions of vegetation dynamics and functions require characterizing resilience, which indicates the capability of an ecosystem to recover from perturbations. Here, using temporal autocorrelation of remotely sensed greenness, we quantify time-varying vegetation resilience during 2000-2019 across northwestern North American Arctic-boreal ecosystems. We find that vegetation resilience significantly decreased in southern boreal forests, including forests showing greening trends, while it increased in most of the Arctic tundra. Warm and dry areas with high elevation and dense vegetation cover were among the hotspots of reduced resilience. Resilience further declined both before and after forest losses and fires, especially in southern boreal forests. These findings indicate that warming and disturbance have been altering vegetation resilience, potentially undermining the expected long-term increase of high-latitude carbon uptake under future climate.

Biostimulant application and green basil biomass production

The aim of this study was to evaluate the influence of the use of the biostimulant Stimulate® on the biomass production of green basil. A randomized block design was used, in a 5x2 factorial scheme with six replications, analyzing different concentrations (0, 5, 10, 15 and 20 mL L-1 of water) and application method (single application and split into 2 times). Harvesting was performed 60 days after transplanting. The variables evaluated were plant height, counting of the number of secondary and tertiary shoots, root length and volume, fresh and dry matter mass, leaf area and essential oil yield. There was no interaction between the concentrations of Stimulate® and the application method. However, there was an increase in all variables analyzed with the concentration of 20 mL per L of water. The application of the biostimulant Stimulate® had an effect on biomass production, plant height, canopy diameter, secondary and tertiary shoots, length and volume of the root system, fresh matter mass of the aerial part and root. Increases in these variables were also observed in response to increased concentrations of Stimulate® and accumulation of green basil essential oil.

Improving yield and irrigation water productivity of green beans under water stress with agricultural solid waste-based material of compacted rice straw as a sustainable organic soil mulch

AbstractThis research aimed at water saving in irrigation by applying deficit irrigation using two strategies, standard drip and partial root drying (PRD), while applying organic and plastic mulch over two growing seasons of green beans. A field experiment was conducted in 2022 and 2023, using four irrigation treatments supplying 100% of the irrigation requirement (IRg), 75% IRg, 50% IRg, and 50% IRg—PRD, and four soil mulching treatments: uncovered soil (UC), plastic mulch (PM), rice straw mulch (RSM), and compacted rice straw mulch (CRSM). The combined effect of deficit irrigation strategies and soil mulching showed that the maximum irrigation water productivity (IWP) of 5.56 kg m−3 was achieved under 50% IRg—PRD &amp; CRSM for both growing seasons, followed by 50% IRg—PRD &amp; RSM and 50% IRg—PRD &amp; PM, with 5.19 and 4.96 kg m−3, respectively. The highest yield of 8936 kg ha−1 was achieved with 50% IRg—PRD &amp; CRSM, followed by 8914 kg ha−1 and 8898 kg ha−1 with 100% IRg &amp; CRSM and 75% IRg &amp; CRSM, respectively. The lowest yield of 6009 kg ha−1 was obtained with 50% IRg &amp; UC. The highest soil moisture content was observed under 100% IRg &amp; CRSM. The application of organic mulches was found to be particularly effective in conserving soil moisture due to enhanced infiltration, improved retention capacity, and suppression of weed growth, ultimately fostering optimal crop development and higher yield. The results of soil temperature variations beneath soil mulches showed that CRSM is effective in alleviating plant water stress, lowering the temperature below the cover and reducing water loss through evaporation from the soil surface. The combination of 50% IRg—PRD &amp; CRSM produced plants with enhanced plant height, fresh and dry weight, leaf area, pod length, and green bean weight, as well as the highest vegetative growth indices. Generally, the organic mulching increased soil temperature, soil moisture, IWP, and green bean production.

ECONOMIC FEASIBILITY STUDY FOR THE IMPLEMENTATION OF A MICRO-INDUSTRY PRODUCING KOMBUCHA FLAVORED WITH PASSION FRUIT FROM THE CAATINGA.

Kombucha is a fermented beverage of Chinese origin produced from the infusion of black or green tea from the Camelia sinensis plant, sugar and a symbiotic culture known as SCOBY. After fermentation, the drink becomes rich in natural nutrients with functions that are beneficial to health such as organic acids, amino acids, vitamin C, polyphenols and antibiotic substances. The present work aims at carrying out a study of the economic feasibility of opening a micro-industry for the production of a black tea kombucha flavored with passion fruit from the caatinga. The caatinga passion fruit is a species native to the dry areas of northeastern Brazil. This fruit is rich in flavonoids, vitamin C and carotenoids, which have antimicrobial and antioxidant properties. For the development of the study, specifications of processes, equipment and analysis of financial and economic indicators were carried out. The evaluation of the investments was carried out using the internal rate of return (IRR), minimum attractiveness rate (TAM), net present value (NPV), simple payback and discounted payback methods. The initial investment for the production of 2,000 L of kombucha flavored with passion fruit from the caatinga was R$ 187,199.78. The economic indicators obtained resulted in NPV of R$ 253,154.68, IRR of 22%, TAM of 13.34% p.a. and simple payback of 3.9 years considering a useful life of 10 years. The positive IRR reflects that the enterprise is economically viable and profitable, making it possible to invest and generate income for cooperatives and family farmers.

Genetic dissection and genomic prediction of drought indices in bread wheat (Triticum aestivum L.) genotypes.

Drought constitutes the main obstacle to agricultural productivity in the Central and West Asia and North Africa (CWANA) region, notably leading to substantial reductions in wheat yields due to terminal water stress. The adoption of drought-resistant wheat varieties appears to be a vital strategy to maintain wheat production in the face of climatic challenges. In this context, a study was conducted utilizing a set of 198 elite bread wheat genotypes developed at the International Center for Agricultural Research in the Dry Areas (ICARDA). This set of elite genotypes was evaluated at the Sidi Al-Aidi station in Morocco over two years (2021-2022), under rain-fed and irrigated conditions. Phenotypic assessments for grain yield and drought indices were performed, alongside genotyping the population using 15k SNP markers. These preparatory steps facilitated a genome-wide association study (GWAS) and genomic prediction, leveraging the Mixed Linear Model (MLM) to pinpoint marker-trait associations (MTAs) and candidate genes pertinent to grain yield and drought indices. The results manifested substantial variations in both grain yield and drought indices among the genotypes tested. Grain yield performance ranged from 0.34 to 2.57 t/ha under rain-fed conditions and 1.12 to 4.57 t/ha under irrigated scenarios. The comprehensive analysis identified 39 significant MTAs (p < 0.001) and 14 putative genes associated with drought indices and grain yield. Noteworthy is the marker “wsnp_Ex_c12127_19394952” on chromosome 5B, which displayed a significant correlation with grain yield in rain-fed environments. Furthermore, the most prominent marker linked to tolerance index (TOL) was “BobWhite_c42349_99”, situated on chromosome 5A and associated with the TraesCS5A02G498000 gene. This gene plays a critical role, encoding for catalase protein crucial for response to hydrogen peroxide. These markers could be used for marker-assisted selection in wheat breeding programs targeting drought tolerance.

Spatiotemporal analysis of wildfires and their relationship with climate and land use in the Gran Chaco and Pantanal ecoregions

The Gran Chaco and Pantanal ecoregions are the largest remaining dry forest areas in South America. Supporting diverse savanna, woodland and wetland ecosystems, these ecoregions are experiencing rapid changes in land use and fire occurrence with implications for ecosystem integrity. Our study characterizes the spatiotemporal patterns of wildfires in the Gran Chaco and Pantanal, and then examines the relationship between patterns of fire occurrence and climatic and anthropogenic drivers. We evaluated fire data of the last two decades (2001-2020) using the MODIS Collection 6.1 and the Global Fire Atlas products. Results of the fire pattern characterization were then used to model the probability of fire occurrence across each ecoregion (Random Forest, Generalized Linear Model, and Generalized Additive Model).Our results indicated that most of the total burned area belonged to the Humid Chaco, while the largest individual burned areas were mainly observed in the Pantanal. Fires primarily occurred during the dry season, with the majority of burned areas recorded during this period. Findings from the three modelling approaches consistently illustrated the spatial distribution of fire occurrence, depicting a declining probability of fire occurrence from East to West. All models underscored the importance of three variables to predict fire occurrence: temperature, livestock abundance and forest cover. Fire occurrence increased with increasing maximum temperatures and livestock presence and decreased with tree cover. This research helps to clarify the potential consequences of changes in land use, rainfall regime and temperature, and uncontrolled burning practices on the current fire activity in the Gran Chaco and Pantanal ecoregions. Understanding the spatiotemporal patterns of fire occurrence and their relationship with climatic, environmental and anthropogenic drivers can help to design more effective management strategies to mitigate fire impacts and to preserve the ecological integrity of these highly diverse regions

Satellite observations indicate that chia uses less water than other crops in warm climates

Many parts of the world face severe and prolonged drought conditions, stressing the sustainability of water resources and agriculture. Transitioning to water-efficient crops is one strategy that can help adapt to water scarcity. An emerging drought-tolerant crop of interest is chia (Salvia hispanica). Yet, no study has compared its large-scale water use dynamics to those of widely established crops across the globe. Here, we use satellite data over multiple years to assess the water use efficiency of chia, alfalfa, corn, and soybean globally. Results show that chia consumed 13-38% less water than alfalfa, corn, and soy and assimilated 14-20% more carbon per amount of water used. Substituting 10% of Southwest United States alfalfa cultivation with chia would save 184 million liters of water per growing season, equivalent to the annual water consumption of 1,300 households. Future research shall explore the economic, societal, and environmental ramifications of substituting alfalfa with chia in dry areas worldwide. These insights can guide decision-makers in promoting sustainable agriculture and water resource management.

Analysis of landscape structure changes in Marmara Lake and its surrounding area using remote sensing data

This study investigates temporal changes in the landscape structure of Lake Marmara (Gölmarmara, Manisa, Türkiye), a designated bird sanctuary and registered wetland, over 10 years period using remote sensing techniques. The analysis employed the Normalized Difference Vegetation Index (NDVI) on satellite imagery from 2015 and 2024, processed through the ArcGIS/ArcMap software, to assess landscape metrics within the study area. The Normalized Difference Water Index (NDWI) was also utilized to evaluate the interactions between the water body, wetlands, and their surroundings. The findings were further supported by surface temperature analysis (STA) and comparative data. NDVI analysis revealed a 39.38% reduction in the Lake Marmara water body, an 11.09% decrease in forested areas, and an 8.28% decline in tree/shrub areas over 10 years. The dominant tree species in the forest vegetation was Pinus brutia, while other prevalent species included Quercus coccifera, Cistus creticus, Pistacia terebinthus, Pistacia lentiscus, Arbutus andrachne, Arbutus unedo, Olea europaea, Erica arborea, Phillyrea latifolia, and Sarcopoterium spinosum. Conversely, residential areas expanded by 21.21%, and agricultural areas increased by 4.11%. NDWI analysis indicated a 14.46% reduction in moderately dry areas and a 41.92% increase in dry areas. Furthermore, surface temperature data showed an increase over the 10 years. This study is expected to contribute significantly to the field by providing insights into sustainable land use and planning strategies. It offers a comprehensive perspective on wetland management and conservation of biological diversity by elucidating the temporal and spatial relationships between wetlands and their environment, considering both ecological and anthropogenic factors.

Global-scale water security and desertification management amidst climate change.

Deserts and semi-arid environments are habitats torare species, rich cultural heritage, and essential ecological processes. Approximately 46% of the world's surface area is covered by drylands (arid, semi-arid, and dry sub-humid areas), where 3 billion people live and unfortunately witness water insecurity and desertification implications. In this context, the present study argued that reduced dryland ecosystem services and decreased ecosystem health have resulted from the individual and compounding impacts of desertification, water scarcity, and climate change. At 1.5°C, 2°C, and 3°C of global warming, under the shared socio-economic pathway SSP2, the number of people living in drylands who will be affected by various effects on water, energy, and land sectors is projected to reach 951 million, 1152 million, and 1285 million, respectively. Due to combinations of land use change, rainfall variations, fire suppression, and CO2 fertilization, as well as unsustainable management, widespread woody encroachment has occurred in many shrublands and savannas in Africa, Australia, North America, and South America. This hasaltered biodiversity and reduces ecosystem services, such as water availability and grazing potential. The north side of the Mediterranean, southern Africa, and North and South America are projected to have the most semiarid expansion. Contrarily, drylands are expected to shrinkin India, northern China, eastern equatorial Africa, and the southern Sahara. Growing research evidence highlights the adoption of policy frameworks deriving the solutions from soil land management (SLM), indigenous and local knowledge (ILK), early warning systems coupled with adaptation and mitigation responses, and targets of sustainable development goals (SDGs).

Common cocklebur (Xanthium strumarium L.) interference in grain sorghum [Sorghum bicolor (L.) Moench]: the influence of weed and crop density.

The common cocklebur (Xanthium strumarium L.) is an invasive weed species in the Asteraceae family that probably originated in Central or South America but has now spread worldwide, where it infests numerous crop fields, including sorghum. It is also a significant invasive weed in various parts of Ethiopia, including the eastern region. In this study field experiments were conducted to investigate the effect of various densities of sorghum and X. strumarium on their growth and reproductive output at Haramaya and Babile Research Stations of Haramaya University in Eastern Ethiopia during the 2022/2023 growing seasons. Sorghum yield loss was greatly affected by X. strumarium density, reaching maximum yield losses of 79.2% and 93.1% at the maximum weed density at Haramaya and Babile, respectively. The presence of X. strumarium in sorghum resulted in reduced aboveground dry matter and leaf area index (LAI). The extent of this reduction depended on the density of X. strumarium. As crop density increased, X. strumarium dry matter, LAI, and bur production m-2 decreased. The highest bur production per unit area for X. strumarium was observed at its highest density (16 plants m-2) with 1097 and 869 burs per unit area at Haramaya and Babile, respectively. These results indicated that higher densities of sorghum were effective in suppressing the bur production of this weed, leading to reduced yield loss. Therefore, sorghum competitiveness against X. strumarium can be improved using higher crop densities. This could play a key role in weed management by reducing the use of herbicides and mechanical controls, thereby forming an important part of integrated weed management. © 2024 Society of Chemical Industry.

How well can satellite altimetry and firn models resolve Antarctic firn thickness variations?

Abstract. Elevation changes of the Antarctic Ice Sheet (AIS) related to surface mass balance and firn processes vary strongly in space and time. Their subdecadal natural variability is large and hampers the detection of long-term climate trends. Firn models or satellite altimetry observations are typically used to investigate such firn thickness changes. However, there is a large spread among firn models. Further, they do not fully explain observed firn thickness changes, especially on smaller spatial scales. Reconciled firn thickness variations will facilitate the detection of long-term trends from satellite altimetry; the resolution of the spatial patterns of such trends; and, hence, their attribution to the underlying mechanisms. This study has two objectives. First, we quantify interannual Antarctic firn thickness variations on a 10 km grid scale. Second, we characterise errors in both the altimetry products and firn models. To achieve this, we jointly analyse satellite altimetry and firn modelling results in time and space. We use the timing of firn thickness variations from firn models and the satellite-observed amplitude of these variations to generate a combined product (“adjusted firn thickness variations”) over the AIS for 1992–2017. The combined product characterises spatially resolved variations better than either firn models alone or altimetry alone. It provides a higher resolution and a more precise spatial distribution of the variations compared to model-only solutions and eliminates most of the altimetry errors compared to altimetry-only solutions. Relative uncertainties in basin-mean time series of the adjusted firn thickness variations range from 20 % to 108 %. At the grid cell level, relative uncertainties are higher, with median values per basin in the range of 54 % to 186 %. This is due to the uncertainties in the large and very dry areas of central East Antarctica, especially over large megadune fields, where the low signal-to-noise ratio poses a challenge for both models and altimetry to resolve firn thickness variations. A large part of the variance in the altimetric time series is not explained by the adjusted firn thickness variations. Analysis of the altimetric residuals indicate that they contain firn model errors, such as firn signals not captured by the models, and altimetry errors, such as time-variable radar penetration effects and errors in intermission calibration. This highlights the need for improvements in firn modelling and altimetry analysis.