Brazilian Semiarid Region Research Articles

What do frog calls tell us about males? The advertisement call of Physalaemus albifrons (Amphibia: Leptodactylidae) in the Brazilian semiarid region does not reflect either gonadal investment or energy storage

ABSTRACT Anuran advertisement calls can provide accurate information on the reproductive quality of the male callers, thus providing females with indicators for the selection of mates. Body size is generally correlated with the dominant frequency of male advertisement calls. However, it is unclear whether and to what extent call parameters are associated with gonadal investment and the energy reserves of the males. Given that in tropical seasonally dry environments the wet season is very short, gathering information about gonadal investment and energy reserves of mates should be particularly important. In the present study, we evaluated the relationship between acoustic performance, gonadal condition, and fat storage in the Neotropical frog Physalaemus albifrons from the Brazilian semiarid region, testing the hypothesis that the advertisement call (repetition rate, call duration, and fundamental and dominant frequencies) would be a good predictor of male quality in terms of gonadal investment (testicle length) and energy reserves (mass of fat bodies). Contrary to our predictions, neither testicle length nor the mass of fat bodies was related to any of the acoustic parameters of the advertisement calls of P. albifrons. These results indicate that the advertisement call of P. albifrons does not provide reliable information on gonadal investment or energy storage of males. Possibly, in habitats with little and unpredictable rainfall, males of P. albifrons should present small variation in gonadal and fat storage conditions during its short reproductive window. Our findings contribute to the understanding of anuran reproductive strategies in seasonally dry environments.

Selecting Bacillus strains antagonist to Erysiphe necator (Schw.) Burr. the causal agent of grape powdery mildew

ABSTRACT Grape powdery mildew (GPM) control is based on the preventive use of sulfur and curative application of synthetic fungicides, increasing the risk for producers’ health and environmental and fruit contamination. This work aimed to select Bacillus strains isolated from the Brazilian tropical semi-arid region that are effective antagonists to GPM. In an initial screening performed by spraying bacterial suspensions in detached grape leaves, six strains of Bacillus spp. showed disease symptom reduction higher than 70.0%. Two greenhouse experiments showed that the bacterial strains LCB03, LCB28, and LCB30 showed control efficiency >80%, statistically similar to a commercial formulation with Bacillus amyloliquefaciens QST713. 16s rDNA sequencing showed that strain LCB03 showed 100.0% homology to B. velezensis, while LCB28 has high homology to B. tequillensis (99.93%), and LCB30 had 99.71% homology with B. siamensis. As an average for both greenhouse experiments, weekly application of Bacillus sp LCB03, Bacillus sp LCB28, and Bacillus sp. LCB30 reduced the average incidence by around 50% and more than 80% for GPM severity.

Calibration and validation of the AquaCrop model for forage cactus production systems under different management interventions in the semi-arid region of Brazil

Simulation models are useful tools for estimating plant response and contributing to the development of management strategies and yield predictions in crops. This study aimed to calibrate and evaluate the AquaCrop-FAO model for the forage cactus imposed on different cropping systems in the semi-arid region of Brazil. Four experiments were conducted: cactus-sorghum intercropping system with five spacings between plants (0.10, 0.20, 0.30, 0.40 and 0.50 m); cactus-sorghum intercropping system with five spacings between rows (1.00, 1.25, 1.50 and 1.75 m); single cactus with four levels of mulch (0, 5, 10 and 15 Mg ha−1); and single forage cactus with four levels of nitrogen fertilisation (50, 150, 300 and 450 kg of N ha−1). The performance of the model was evaluated using the following parameters: root mean squared error (RMSE); normalised RMSE (NRMSE), coefficients of determination (R2), Nash-Sutcliffe model efficiency coefficient (ME) and the Willmott index of agreement (d). During the calibration stage, the statistical indices pointed to the good performance of the AquaCrop model in estimating dry biomass in most of the cropping systems, with 10 < NRMSE <20; R2 > 0.96 and ME > 0.95. The AquaCrop model showed the best performance simulating systems under different levels of nitrogen fertilisation. Among the intercropping systems, the denser arrangements showed the highest values for simulated biomass.

The Effect of Using Compost on Cowpea Productivity in the Semi-Arid Region of Brazil

The production of cowpea is part of the agricultural activities of farmers in the semi-arid region of Brazil, being important in the aspect of acquiring income and source of food, in this sense, the use of rooster tree (Calotropis procera) mixed with cattle manure in cowpea productivity in the semi-arid region of Brazil. The experiment was conducted from August to November 2023 at the Rafael Fernandes experimental farm, in the district of Alagoinha (5º03'37 "S, 37º23'50" W), northwest of Mossoró, State of Rio Grande do Norte, Brazil, with an area of 400 hectares. The experimental design used was randomized complete blocks in a 4 x 2 factorial scheme, with three replications. The first factor consisted of four quantities of cattle manure (0.0; 1.1; 2.2 and 4.4 kg m-2), the second factor being the presence and absence of rooster tree. Each plot consisted of dimensions of 2.2 m x 1.2 m, with a total area of 2.64 m2. Each plot had eight holes with three plants, making a population of 90,900 plants ha-1. After harvesting the dried pods, they were stored in plastic bags, identified and taken to the DCAF/UFERSA Post-Harvest laboratory, where the following characteristics were measured: pod length, expressed in cm, number of pods plant-1, expressed in plant-1 units, weight of five pods, expressed in grams, weight of 100 grains, expressed in grams and dry grain productivity, expressed in kg ha-1. The highest cowpea productivity was observed at a dose of 4.4 kg m-2, with a maximum value of 2,858.85 kg ha-1. The presence of rooster tree did not influence any of the characteristics evaluated. The use of cattle manure is an option for farmers in the semi-arid region.

Evaluation of a solar-driven adsorption desalination system for Brazilian semiarid region

In this study, the effect of using a hybrid solar thermal-activated adsorption desalination system for brackish water is evaluated under the climatic conditions of the Brazilian semiarid region. The proposed theoretical model utilizes climatic data from the meteorological station in Campina Grande, PB, and adsorptive kinetics data of Fuji Davison RD 260 silica gel to predict the performance indices of the specific daily water production (SDWP), specific cooling power (SCP), and coefficient of performance (COP) performance coefficients over a characteristic day. The SDWP value of 6.26 m3/ton, SCP ranging from 50 to 300 W/kg, and an average COP of 0.5 were obtained, considering variations in global horizontal irradiance in the ACDS system and transient ambient temperature. It was observed that both the production of desalinated water and the refrigeration effect increase with the rise in daily solar irradiance. The variation in the number of solar collectors used in the system and their optimality, as well as the variation in the salinity index of the feed source, impacted the evaluated performance coefficients.

Classification of expansive soils among problematic soils in the brazilian semiarid from artificial neural networks

The climatological and geomorphological conditions of the Brazilian semiarid region favor the formation of potentially expansive soils. The development of neural networks to identify and classify expansive soils in Pernambuco, and the need to export to soils across the semiarid region of Brazil is investigated in this study using a Multi-Layer Perceptron (backpropagation). The neural network was developed using 87 experimental data points, divided into three groups. The Training Group, consisting of 53 samples, using data inputs: sand percentage, clay percentage, plasticity index, activity index, and geological, pedological, and climatological classification. Selection Group, made up of 17 samples, was used to select the best network architecture, genetics algorithms formed of 7 inputs and 3 hidden nodes. The Test Group used 17 samples to evaluate the predictive accuracy of the expansion potential, obtaining an accuracy rate of 88,2%. This network was validated by applying it to 67 samples of problematic soils of the collapsible, expansive, and soft type from the Brazilian semiarid region, reaching an accuracy of 76,1%. Probabilistic Neural Networks were found to be efficient in evaluating the behavior of expansive soils, with the ability to deal with the absence of sample input data, demonstrating the ability to capture movement trends in the expansion of the soil surface, indicating the functions that introduce the effects of the composition potential on the expansion behavior, and determining the limit values of each of the input variables for the samples from the database used.

Drivers of richness and abundance of parasites of fishes from an intermittent river before and after an interbasin water transfer in the Brazilian semi-arid region.

This study examined the metrics of the macroparasite community in fishes from the Jaguaribe River basin, state of Ceará, before and after receiving water from the São Francisco River in Northeastern Brazil. This research assessed the association of environmental factors (water parameters) and the traits of 30 fish species on the parasite richness and abundance across space (river course) and time (seasons, pre- and post-transposition periods). Generalized linear models reveal associations between parasite metrics and host traits, water parameters, and river sub-basin. Host size and body condition positively correlated with parasite richness and abundance, while reproductive phase was negatively related. Water quality impacted ecto- and endoparasites differently, with seasonal and sub-basins variations and differences among sub-basins. The general models also indicate that the period is a significant variable, where parasite richness decreases while abundance increases in the post-transposition period. This study underscores the importance of considering diverse environmental and host variables for understanding parasite dynamics in river ecosystems. These findings could lead to valuable insights for ecosystem management and conservation, elucidating the potential consequences of environmental alterations on parasite-host interactions and ecosystem health.

Seasonal Influence on the Feeding Patterns of Three Sympatric Tropidurus Lizards (Squamata: Tropiduridae) of the Caatinga, in the Brazilian Semi-Arid Region

Seasonal Influence on the Feeding Patterns of Three Sympatric Tropidurus Lizards (Squamata: Tropiduridae) of the Caatinga, in the Brazilian Semi-Arid Region

The diversity of soil-dwelling arthropods is significantly influenced by land use systems with tree cover in semiarid conditions

Seasonal changes in vegetation and climate exert significant influences on soil fauna in natural and agricultural ecosystems. Additionally, evidence indicates that interactions between different plant layers promote soil fauna diversity through the variety of resources available. The objective was to assess the edaphic fauna in traditional land use systems, agroforestry systems and natural vegetation, under the influence of rainfall seasonality and plant strata in the semiarid region of Brazil. For this purpose, six types of land use were selected: agroforestry; silvopastoral; slash and burn with intensive use without fallow; slash and burn with six years of fallow; slash and burn with nine years of fallow; and a system representing the natural vegetation of the Caatinga. Edaphic fauna was collected using pitfall traps in the dry and rainy seasons. A total of 43,363 individuals of the edaphic fauna were collected and grouped into taxa, determining abundance, diversity and functional groups. The results revealed higher abundance and diversity of edaphic fauna in the rainy season across all land use systems, but significantly higher numbers in systems with tree strata. The greater the abundance, richness and diversity of trees, the higher the diversity of edaphic fauna (Shannon Index - H: 0.7 < ‾H < 1) for the seasonal effect. Agroforestry systems were intermediate in the diversity of edaphic fauna (‾H < 0.8) compared to other systems. Systems with greater heterogeneity in tree and herbaceous strata were the ones that most increased the diversity and activity of functional groups of edaphic fauna (H < 0.8; 0.5 < r < 0.9). In semiarid conditions, more attention should be given to agricultural production systems with greater tree diversity and interaction between tree and herbaceous strata to conserve the biodiversity of edaphic fauna and improve the soil health.

Supplementation with NPK Prior to Water Restriction Confers Different Biochemical and Growth Modulations in a Native and Exotic Species Present in a Brazilian Semi-arid Region

Supplementation with NPK Prior to Water Restriction Confers Different Biochemical and Growth Modulations in a Native and Exotic Species Present in a Brazilian Semi-arid Region

Update on the geographical distribution of freshwater crabs of the Pseudothelphusidae family in the semi-arid region of northeastern Brazil

The humid forest zones of northeastern Brazil are recognized as endemic hotspots for pseudothelphusid crabs. In this study, we report new occurrence records of the pseudothelphusids, Fredius ibiapaba and Kingsleya attenboroughi, in humid soil and streams within humid forests of the semi-arid region of northeastern Brazil. These new records expand the geographical distribution of these crabs, highlighting their potential to inhabit humid forests throughout this region. Furthermore, this information indicates that these crabs, especially K. attenboroughi, are not confined to slopes and patches of humid forests in highland swamps but can also extend to springs in other areas of the Brazilian semi-arid region.

Economics of small-scale aquaculture farms in Brazilian Northeastern semi-arid region: Characteristics, feasibility, and profitability models

Inland aquaculture represents a significant component of the aquaculture sector in Brazil. This activity is present in all Brazilian regions, yet the economic feasibility and the relationship between their productive variables and profitability indices remain poorly accessed in Brazil's semi-arid regions. This study aims to characterise, assess the economic feasibility, and evaluate the relationship between productive variables and profitability indices in the aquaculture sector in Feira Nova (Northeast Brazil). The data was collected through interviews with all producers in Feira Nova city and modelled using the software R. The aquaculture sector in Feira Nova is predominantly small-scale and encompasses a wide range of production strategies for shrimp and fish cultures, with profitable outcomes. The models demonstrated that economic and management variables were more closely associated with profitability indices than farm characteristics such as farm size. Feira Nova's profitability indices reinforces the small-scale aquaculture as a promising activity to alleviate poverty and generate wealth in Brazil semi-arid regions. However, governance improvements are necessary to boost the development of inland aquaculture in the country.

Childhood obesity is associated with a high degree of metabolic disturbance in children from Brazilian semi-arid region

Projected to impact 310 million children by the next decade, childhood obesity is linked to serious health issues like metabolic disturbance and cardiovascular diseases. This study introduces a novel approach for the integrated assessment of inflammatory, glycemic and lipid disorders in obese children in resources-limited settings and also identifies key factors contributing to these changes. Conducting a cross-sectional analysis of 231 children aged 5–12 years from public schools in Brazil's semi-arid region, the research involved collecting medical history, anthropometric measurements, and blood samples to analyze glycemic and lipid profiles, along with C-reactive protein levels. We used an adapted the Molecular Degree of Perturbation model to analyze deviations in metabolic markers from a healthy control group. Statistical analyses included Mann–Whitney and Fisher exact tests, backward logistic regression, and hierarchical cluster analysis. The study identified a direct and independent association between elevated Metabolic Disturbance Degree and both overweight and obesity in children, with significant differences in CRP, Triglycerides, and HDL levels noted between obese and healthy-weight groups. The findings highlight the critical need for early detection and comprehensive understanding of obesity-related changes to mitigate the severe health risks associated with childhood obesity.

Evaluating Daily Water Stress Index (DWSI) Using Thermal Imaging of Neem Tree Canopies under Bare Soil and Mulching Conditions

Water stress on crops can severely disrupt crop growth and reduce yields, requiring the accurate and prompt diagnosis of crop water stress, especially in semiarid regions. Infrared thermal imaging cameras are effective tools to monitor the spatial distribution of canopy temperature (Tc), which is the basis of the daily water stress index (DWSI) calculation. This research aimed to evaluate the variability of plant water stress under different soil cover conditions through geostatistical techniques, using detailed thermographic images of Neem canopies in the Brazilian northeastern semiarid region. Two experimental plots were established with Neem cropped under mulch and bare soil conditions. Thermal images of the leaves were taken with a portable thermographic camera and processed using Python language and the OpenCV database. The application of the geostatistical technique enabled stress indicator mapping at the leaf scale, with the spherical and exponential models providing the best fit for both soil cover conditions. The results showed that the highest levels of water stress were observed during the months with the highest air temperatures and no rainfall, especially at the apex of the leaf and close to the central veins, due to a negative water balance. Even under extreme drought conditions, mulching reduced Neem physiological water stress, leading to lower plant water stress, associated with a higher soil moisture content and a negative skewness of temperature distribution. Regarding the mapping of the stress index, the sequential Gaussian simulation method reduced the temperature uncertainty and the variation on the leaf surface. Our findings highlight that mapping the Water Stress Index offers a robust framework to precisely detect stress for agricultural management, as well as soil cover management in semiarid regions. These findings underscore the impact of meteorological and planting conditions on leaf temperature and baseline water stress, which can be valuable for regional water resource managers in diagnosing crop water status more accurately.

Can changes in land use in a semi-arid region of Brazil cause seasonal variation in energy partitioning and evapotranspiration?

Changes to forests due to deforestation, or their replacement by agricultural areas, alter evapotranspiration and the partitioning of available energy. This study investigated seasonal variations in the energy balance and evapotranspiration in landscapes under different levels of anthropogenic intervention in the semi-arid region of Brazil. Micrometeorological data was obtained from September 2020 to October 2022 for three areas of the semi-arid region: preserved Caatinga (CAA, native vegetation), Caatinga under regeneration (REGE) and a deforested area (DEFA). Here, we use the Bowen ratio energy balance method. Measurements were taken of global solar radiation, air temperature, relative humidity, vapour pressure deficit, rainfall, net radiation, latent heat flux, sensible heat flux, soil heat flux, evapotranspiration, volumetric soil water content and Normalised Difference Vegetation Index. Sensible heat flux was the dominant flux in both areas with 66% for preserved Caatinga vegetation, 63% for Caatinga under regeneration and 62% deforested area. The latent heat flux was equivalent to 28% of the net radiation for preserved Caatinga vegetation, Caatinga under regeneration and deforested area. The evapotranspiration in turn responded as a function of water availability, being higher during the rainy seasons, with average values of 1.82 mm day−1 for preserved Caatinga vegetation, 2.26 mm day−1 for Caatinga under regeneration and 1.25 mm day−1 for deforested area. The Bowen ratio presented values > 1 in deforested area, preserved Caatinga vegetation and Caatinga under regeneration. Thus, it can be concluded that the change in land use alters the energy balance components, promoting reductions in available energy and latent and sensible heat fluxes during the rainy-dry transition in the deforested area. In addition, the seasonality of energy fluxes depends on water availability in the environment.

Ewe-lamb bond at birth and during lactation in an equatorial semi-arid environment is better in a native than in an introduced breed

Santa Ines and Dorper sheep are the most popular breeds in the Brazilian semi-arid region. The former is of local origin and less intensively selected for productivity, and the latter is an introduced exotic breed selected for meat production. Dorper lambs are heavier at birth than Santa Ines lambs, which might increase the need for birth assistance, negatively influencing the newborn and maternal behaviours. Dorper lambs grow faster, most likely influencing their behavioural strategies during lactation, depending less on their mother than Santa Ines lambs. The aim of this study was to compare the behaviours of Santa Ines and Dorper ewes and their lambs at birth and throughout lactation. A complementary aim was to determine if being single or twin lambs impact differently according to the breed. Twenty-five Santa Ines ewes and their 32 lambs (18 single and 14 twins) and 21 Dorper ewes and their 26 lambs (16 single and 10 twins) were used in the study. Mother-offspring behaviours were recorded from birth until 63 days after lambing. Dorper ewes had a greater incidence of dystocia (P = 0.02) and longer labour (P = 0.0001) than Santa Ines ewes. At birth, Santa Ines ewes displayed a greater frequency of low-pitched bleats (P = 0.0006) and tended to spend more time grooming their lambs than Dorper ewes (P = 0.07). Immediately after birth, Santa Ines lambs shook their head earlier than Dorper lambs (P = 0.003). The litter size effects were unrelated to the breed: ewes of single deliveries groomed their lambs earlier (P = 0.04), and those that delivered twins spent more time grooming the first lamb delivered (P = 0.01). Over the first two weeks after parturition, Santa Ines ewes displayed higher frequencies of head-up postures (P = 0.0001), high-pitched bleats (P = 0.02) and smelled their lambs more times (P = 0.0001) than Dorper ewes. Santa Ines lambs were closer to their mother when grazing (P = 0.0001), while Dorper lambs were closer to their mother when lying down (P = 0.049). In conclusion, Santa Ines sheep shows a stronger ewe-lamb bond than Dorper soon after parturition, and such differences persist at least until 9 weeks after lambing. The ewe-lamb bond was weaker in twin than single lambs, without differences in the degree of its strength between Santa Ines and Dorper sheep.

New synonyms and lectotypifications in Sida (Malvaceae-Malveae) reveal the first record and extension of the distribution area of Sida maculata to Brazil

New synonyms and lectotypes in Sida sect. Cordifoliae (Malvaceae, Malveae) are proposed here and reveal the first record and extension of the distribution area of Sida maculata to the Brazilian semi-arid region. The species was first described in the 18th century for the Caribbean islands of Cuba and the Dominican Republic and for a long time was confused with S. cordifolia, from which it is unquestionably distinct in its leaves, inflorescences and flowers. In Brazil, S. maculata is widely distributed from Maranhão to the north of Minas Gerais and was identified for almost a century in herbaria and local floristic treatments as S. galheirensis. Discussions and photographs of types of S. maculata and related taxa are presented, as well as an updated map of the species’ geographical distribution.

Environmental vulnerability applied to the territorial planning of a tropical semiarid basin.

Tropical semiarid regions are naturally prone to environmental damage. Human activity can worsen this situation. To understand how human actions affect the ecosystem, plan land use effectively, and establish targeted management practices, assessing environmental vulnerability is crucial. This study focuses on a sub-basin receiving water transfers from the São Francisco River in Brazil's semiarid region. Here, we map and evaluate how land use and occupation alter natural vulnerability. We also propose zoning strategies to support water resource management and implement sustainable development policies in the region. To achieve this, we conducted an integrated analysis of physical factors (soil types, geology, climate, vegetation, and landforms) and spatial land-use data using geographic information systems (GIS) and map algebra techniques. Map algebra allowed us to combine these various datasets within the GIS environment, enabling the creation of maps that synthesize both natural and environmental vulnerability across the study area. Following analysis of these vulnerability maps, our findings reveal a high level of vulnerability. The areas with high to very high degrees of natural vulnerability coincide with the places that have high slopes, high altitudes, Lithic Neosols, and thick vegetation. Furthermore, the interaction between environmental factors and human activity exacerbates vulnerability. Based on the environmental vulnerability assessment, we defined four environmental management zones. These zones require distinct protection measures and management approaches. As a method to potentially improve the basin's vulnerability scenario, soil conservation measures are recommended. This approach is highly relevant for managing land in tropical semiarid regions and, with adaptations to specific regional factors, can be applied globally.

New records of Cassidinae and Cerambycidae (Coleoptera: Chrysomeloidea) from Baturité Massif, Brazil, with the description of a new species of Charidotis (Coleoptera: Chrysomelidae: Cassidinae)

The Baturité massif, situated in Ceará state’s central hinterland, is one of the largest humid mountain ranges in the Brazilian semi-arid region. Flora and vertebrate surveys have been conducted in the region, revealing endemic species, as well as a combination of fauna and flora from neighboring biomes, the Atlantic and Amazon rainforests. However, invertebrate inventories have been scarce, leaving a significant portion of the region’s biodiversity unexplored. This paper presents the outcomes of collaborative expeditions conducted by the recently established Museu de História Natural do Ceará Prof. Dias da Rocha and Museu Nacional/Universidade do Rio de Janeiro to fill this knowledge gap by promoting surveys to document the region’s biodiversity. As a result, one new species of tortoise beetle is described from the massif, Charidotis rochai Simões and Sekerka, new species. Additionally, we report thirteen new state records for the beetle subfamilies Cassidinae (Chysomelidae), and Cerambycinae and Lamiinae (Cerambycidae). Among these records, eight genera are documented for the first time in the state of Ceará, and the species Centrocerum variatum (Newman, 1841) constitutes the first record in the northeastern region of Brazil. These findings underscore the significance of survey initiatives and the need for comprehensive biodiversity study within the Baturité massif.

Effect of cattle manure on soil compaction in the brazilian semi-arid region

Soil organic matter is seen as the most important factor in the assessment of soil management systems that affect soil quality and agricultural sustainability. Cattle manure added to crop residues left on the surface of the soil or incorporated have been used on agricultural properties in the semi-arid region of Brazil in the crop-livestock production system as an alternative for sustainable production. However, information on the benefits that this system can bring regarding the physical and mechanical properties of the soil is still limited. The objective of this study was to evaluate the effect of cattle manure on soil susceptibility to compaction, using the Proctor test. Samples of a “Neossolo Fluvico Ta Eutrofico” were collected at depths of 0 to 5 cm, 5 to 10 cm and 10 to 20 cm of an area cultivated with corn in the semi-arid region of Brazil. The Proctor test was carried out in the laboratory with samples obtained from depths of 0 to 5cm and 5 to 10cm without and with the addition of 15% and 30% of cattle manure. The experimental design was randomized blocks, arranged in a 3x2x3 factorial consisting of soil without manure, soil with 15% manure and soil with 30% manure from both depths and three replications. The maximum soil density, water content and organic carbon were evaluated. The results indicate that cattle manure can be an effective alternative in crop-livestock production systems on agricultural properties in the Brazilian semi-arid region, reducing soil compaction and leveraging agribusiness with sustainability.