Semi-arid Northeastern Brazil Research Articles

Intermittent development of forest corridors in northeastern Brazil during the last deglaciation: Climatic and ecologic evidence

The semi-arid northeastern (NE) Brazil vegetation is largely dominated by Caatinga, one of the largest and richest dry forests in the world. Caatinga is a strategic biome, since it has borders with Cerrado, Atlantic forests and the Amazon, acting as a potential corridor (or barrier) for biotic interchange between these regions during evolutionary times. Therefore, accurate reconstructions of past vegetation, ecological and hydrological changes in this area are critical to understanding the dynamics of biome boundaries that may play an important role in dispersal and diversification mechanisms and, more specifically, the link between the long-term climate variability and tropical biodiversity. Here, we present high-resolution palynological and elemental data from marine core GeoB16205-4 retrieved off the Parnaíba River mouth (NE Brazil) mainly covering the Younger Dryas (YD). We show that the YD interval was predominantly wet in NE Brazil, yet it was not homogenous and two distinct phases could be distinguished. A marked intensification of wet conditions between ∼12.3 and 11.6 cal kyr BP was recorded by the expansion of tropical rainforest and tree ferns. These results are in agreement with the transient TraCE-21k coupled climate model simulation. We infer that the second pluvial phase of the YD is related to a weak AMOC due to meltwater pulses in the North Atlantic, which forces a southward shift of the Intertropical Convergence Zone and its associated rainfall. Our records provide new evidence on the establishment of an “eastern forest corridor” in the nowadays semi-arid Caatinga allowing for past biotic interchanges of plant species.

Helminth Parasites of the Lizard Nothobachia ablephara (Gymnophthalmidae) in Caatinga Areas from the Sertão of Brazil.

The lizard Nothobachia ablephara is endemic to dune areas and sandy soils adjacent to the São Francisco River in semiarid northeastern Brazil. Forty-nine lizard specimens were collected in 2 Caatinga areas in the municipality of Petrolina in Pernambuco state. Three gastrointestinal helminth taxa were identified, the nematodes Parapharyngodon alvarengai and Physaloptera sp. and the cestode Oochoristica sp. Nothobachia ablephara showed low parasite richness, but high levels of infection by P. alvarengai. There were no significant differences between the parasitism rates of the 2 study areas or between male and female lizards. This is the first study on parasitism in N. ablephara, thereby increasing knowledge of parasite fauna that infect gymnophthalmid lizards in the Sertão of Brazil.

Evaluation of the Wind Fields in the Semi-Arid Region in Northeastern Brazil Using RAMS Model

Abstract The use of wind power has increased significantly around the world over the last few years. Some estimates state that about 12% of all energy generated in the world will come from wind energy conversion systems, corresponding to an installed capacity of 1,200 GW. The installed wind power capacity in Brazil is low, being equal to 11300 MW in 2017. Even though Brazilian wind potential is not spread all over the country, some regions are quite interesting for the installation of wind farms, especially the Northeast region, which aggregates about 53% of the national potential. This work aims to identify patterns of variability of the wind regime, as well as potential sites for the generation of wind power in semi-arid northeastern Brazil. In order to achieve it, numerical simulations are performed using the Regional Atmospheric Modeling System (RAMS). During simulations, both turbulence parameterization and Newtonian relaxation time scale are evaluated. It is worth to mention that obtained data are compared with those provided by the National Institute of Meteorology (INMET) through static indexes.

Impact of filamentous cyanobacteria on the water quality of two tropical reservoirs

ABSTRACT Artificial lakes play an important role in water availability in tropical semi-arid Northeastern Brazil. However, in addition to the negative effects that dams have on the water quality of rivers, other practices such as discharge of untreated wastewater, intensive crop fertilization and fish farming have been contributing to water quality deterioration. Climate change may be another driver of water quality decrease. Increases in precipitation and drought intensities as well as temperature increase may redefine the dynamics of planktonic communities and favour species more adapted to the new environment. Water samples were collected in two reservoirs selected based on the recurrence of positive results for saxitoxins, Acarape do Meio (AM) and Sitios Novos (SN). In general, diversity in SN (1.08) was higher than in the AM (0.60). Phytoplankton dynamics in these reservoirs differ from other reservoirs in the same region of Brazil, in the sense that filamentous cyanobacteria are dominant. Furthermore, lower diversity, concentration and richness of chlorophyceae and bacillariophyceae were found in both reservoirs. Increase in diversity was observed during the intense rainy season of 2011, suggesting a slight improvement of water quality. A close inverse correlation between Cylindrospermopsis sp and other cyanobacteria was found in SN (R2= –0.862) and in AM (R2= –0.997) and the data collected demonstrates that a season with intensive rainfall may lead to lower cyanobacteria concentrations probably due to water dilution and higher flushing rates.

PERMANENCE OF WATER EFFECTIVENESS IN THE ROOT ZONE OF THE CAATINGA BIOME

ABSTRACT Soil is an important water compartment into a watershed scale, mainly due to its role in providing water to plants and to the influence of antecedent moisture on the runoff initiation. The aim of this research is to assess the permanence of water effectiveness in the soil under preserved-vegetation constraints in the Caatinga biome, in the semiarid northeastern Brazil. For this purpose, hourly soil moisture measurements were collected with TDR and analyzed between 2003 and 2010 for three soil-vegetation associations in the Aiuaba Experimental Basin. The results showed that in nine months per year soil moisture was below wilting point for two associations, whose soils are Chromic Luvisol and Haplic Lixisol (Abruptic). In the third association, where the shallow soil Lithic Leptosol prevails, water was found non-effective four months per year. A possible reason for the high water permanence in the shallowest soil is the percolation process, generating sub-surface flow, which barely occurs in the deeper soils. In situ observations indicates that the long period of soil moisture below the wilting point was not enough to avoid the blooming season of the Caatinga vegetation during the rainy periods. Indeed, after the beginning of each rainy season, there is a growth of dense green vegetation, regardless of the long period under water shortage.

High Primary Production Contrasts with Intense Carbon Emission in a Eutrophic Tropical Reservoir.

Recent studies from temperate lakes indicate that eutrophic systems tend to emit less carbon dioxide (CO2) and bury more organic carbon (OC) than oligotrophic ones, rendering them CO2 sinks in some cases. However, the scarcity of data from tropical systems is critical for a complete understanding of the interplay between eutrophication and aquatic carbon (C) fluxes in warm waters. We test the hypothesis that a warm eutrophic system is a source of both CO2 and CH4 to the atmosphere, and that atmospheric emissions are larger than the burial of OC in sediments. This hypothesis was based on the following assumptions: (i) OC mineralization rates are high in warm water systems, so that water column CO2 production overrides the high C uptake by primary producers, and (ii) increasing trophic status creates favorable conditions for CH4 production. We measured water-air and sediment-water CO2 fluxes, CH4 diffusion, ebullition and oxidation, net ecosystem production (NEP) and sediment OC burial during the dry season in a eutrophic reservoir in the semiarid northeastern Brazil. The reservoir was stratified during daytime and mixed during nighttime. In spite of the high rates of primary production (4858 ± 934 mg C m-2 d-1), net heterotrophy was prevalent due to high ecosystem respiration (5209 ± 992 mg C m-2 d-1). Consequently, the reservoir was a source of atmospheric CO2 (518 ± 182 mg C m-2 d-1). In addition, the reservoir was a source of ebullitive (17 ± 10 mg C m-2 d-1) and diffusive CH4 (11 ± 6 mg C m-2 d-1). OC sedimentation was high (1162 mg C m-2 d-1), but our results suggest that the majority of it is mineralized to CO2 (722 ± 182 mg C m-2 d-1) rather than buried as OC (440 mg C m-2 d-1). Although temporally resolved data would render our findings more conclusive, our results suggest that despite being a primary production and OC burial hotspot, the tropical eutrophic system studied here was a stronger CO2 and CH4 source than a C sink, mainly because of high rates of OC mineralization in the water column and sediments.

Assessment of schistosomiasis in the semi-arid Northeast region of Brazil: the São Francisco River large-scale water transposition project.

INTRODUCTION Risk of schistosomiasis expansion to semi-arid northeastern Brazil under the influence of the Integration Project of the São Francisco River (IPSFR) was assessed. Stool examinations of schoolchildren, epidemiological investigation, and survey of the local host snail Biomphalaria straminea were performed in five IPSFR municipalities. RESULTS Six of 4,770 examined schoolchildren were egg-positive for Schistosoma mansoni. Biomphalaria straminea was widespread, but not naturally infected with S. mansoni. Snails experimentally exposed to two laboratory S. mansoni strains yielded infection indices of 1-4.5%. There is evidence of active schistosomiasis transmission in the area; thus, intensive surveillance actions are required.

Botanical composition of Caatinga rangeland and diets selected by grazing sheep

Sheep dietary selection from species-diverse Caatinga rangeland of semi-arid northeastern Brazil has not been documented. This study examined the botanical composition of the available forage and diets of Dorper x Saint Ines ewes on thinned Caatinga over-seeded with Cenchrus ciliaris and Urochloa mosambicensis . Sixty-three species from 23 families, dominated by shrubs and short trees of low forage nutritive value, were identified in the vegetation. The botanical composition revealed, on average, high presence of 29.2% Malvaceae and 13.0% C. ciliaris . Using the microhistological technique, sheep showed, on average, 59.6% preference for dicotyledons throughout the year. However, selectivity indexes indicated, on average, greater selection for Poaceae during the rainy season (1.5) and for dicotyledons in the dry season (1.8) with a year-round aversion for Malvaceae (0.3). These findings suggest that Caatinga vegetation management should include Malvaceae thinning and greater incorporation of grasses and herbaceous legumes to improve rangeland carrying capacity. Keywords: Brazil, continuous stocking, dietary selection, microhistological technique, principal components. DOI: 10.17138/TGFT(4)71-81

Ichthyofauna of the humid forest enclaves in the tablelands of Ibiapaba and Araripe, Northeastern Brazil

Abstract Humid highland forest enclaves are remnants of Atlantic Forest found in tablelands within the Caatinga biome (Northeastern Brazil), which emerged during interglacial periods in the Pleistocene. These ecosystems have a highly diverse and endemic fish fauna. Most earlier surveys have focused on the tableland of Borborema (Pernambuco and Paraíba States). In this study we surveyed the fish fauna of the humid forest enclaves in the tablelands of Ibiapaba and Araripe, based on samples collected in the rainy season (March and April) between 2009 and 2014. The 45 sampling points covered rivers, streams and reservoirs in five river basins belonging to three ecoregions. The species were listed according to drainage divide, and endemism was determined for each ecoregion and for the Caatinga. Our area was more species-rich (n=59) than Borborema (n=27). The samples included five introduced species and 29 species endemic to the Caatinga (49.1% of the sampled species). The distribution of Parotocinclus haroldoi was expanded to the Mid-Northeastern Caatinga ecoregion (Timonha river basin, Ceará State). Our study intends to make a significant contribution to current knowledge of the ichthyofauna in humid highland forest enclaves of semiarid Northeastern Brazil, identified as a priority in the conservation of the biodiversity in the Caatinga.

Drought-induced water-level reduction favors cyanobacteria blooms in tropical shallow lakes

Many arid and semiarid regions are likely to become warmer and drier by the end of this century, due to human-induced climate change. We hypothesize that a reduction in water level caused by droughts will aggravate eutrophication, leading to higher cyanobacteria biomass and dominance in tropical regions. To test this hypothesis, we analyzed physical and chemical variables and plankton communities of 40 man-made lakes in warm semiarid northeastern Brazil at the end of the wet and dry seasons. We also constructed a predictive model of cyanobacteria biovolume in these lakes. The lakes had significantly lower water volume, transparency, and CO2 concentrations but higher water temperature, water column stability, electrical conductivity, pH, suspended solids, ammonium, total nitrogen concentrations, bacteria biomass, phytoplankton biomass, and cyanobacteria biomass and dominance in the dry than in the wet season. Our regression model suggested that cyanobacteria biovolume was positively related to water column stability, pH, and total nitrogen and negatively related to water transparency and concentrations of inorganic suspended solids. These results suggest that the projected warmer and drier climate in the future will reduce water quantity and quality of man-made lakes in the region, increasing the risks of salinization, anoxia, eutrophication, and cyanobacteria blooms.

Termite mounds as dominant land forms in semiarid northeastern Brazil

Open source satellite imagery has allowed the visualization and mapping of remarkable numbers of large, densely-packed termite mounds covering extensive areas in the semiarid region of northeastern Brazil, revealing tens of millions of regularly spaced termitaria (between 2 and 4 m tall, at densities of up to 35/ha). The origin, distribution, and natural history of these mounds are discussed, as well as questions regarding their age and dense packing, their sharing or appropriation by other insects, and why they attained such huge volumes in a dry landscape.

Increasing efficiency in ethanol production: Water footprint and economic productivity of sugarcane ethanol under nine different water regimes in north-eastern Brazil

Ethanol production in Brazil has grown by 219% between 2001 and 2012, increasing the use of land and water resources. In the semi-arid north-eastern Brazil, irrigation is the main way for improving sugarcane production. This study aimed at quantifying water consumed in ethanol production from sugarcane in this region using the water footprint (WF) indicator and complementing it with an evaluation of the water apparent productivity (WAP). This way we were able to provide a measure of the crop´s physical and economic water productivity using, respectively, the WF and WAP concepts. We studied sugarcane cultivation under nine different water regimes, including rainfed and full irrigation. Data from a mill of the state of Alagoas for three production seasons were used. Irrigation influenced sugarcane yield increasing total profit per hectare and economic water productivity. Full irrigation showed the lowest WF, 1229 litres of water per litre of ethanol (L/L), whereas rainfed production showed the highest WF, 1646 L/L. However, the lower WF in full irrigation as compared to the rest of the water regimes implied the use of higher volumes of blue water per cultivated hectare. Lower water regimes yielded the lowest economic productivity, 0.72 US$/m3 for rainfed production as compared to 1.11 US$/m3 for full irrigation. Since economic revenues are increased with higher water regimes, there are incentives for the development of these higher water regimes. This will lead to higher general crop water and economic productivity at field level, as green water is replaced by blue water consumption.

Estudo fitossociológico de uma área de Caatinga na Estação Ecológica (ESEC) de Aiuaba, Ceará, Brasil

The goal of this work was to characterize the physiognomy and structure of the woody component of an area of caatinga vegetation in the Estacao Ecologica (ESEC) of Aiuaba, Ceara state, thereby contributing to the knowledge of the vegetation of semiarid northeastern Brazil. Fifty sampling plots (10x10m) were randomly established in a 1.5 hectare area, where stem diameter at soil level was ≥ 3 cm and height was ≥ 1 m. The survey results included 3,007 individuals from 47 species and 20 families. Fabaceae, Euphorbiaceae, Erythroxylaceae, Acanthaceae, Bignoniaceae and Rutaceae represented 66% of the species, and the first three families represented 63% of the total importance value. Croton argyrophylloides Mull. Arg., Pityrocarpa moniliformis Benth., Erythroxylum caatingae Plowman and Bauhinia cheilantha (Bong.) Steud. were the most important species. Average plant height was 4.51 m, with a maximum of 13 m; average stem diameter was 7.28 cm, with a maximum of 44.88 cm. The total basal area was 18.3 m2 ha-1. The plant community can be classified as a type of caatinga with shrubs and trees, presenting similar floristic composition to other caatinga vegetation in areas of sandy sediments, and to non-thorn deciduous vegetation (“carrasco”) situated in the Ibiapaba-Araripe Complex.

English

Paclobutrazol (PBZ) is a plant growth regulator, increasing flowe ring and yield that is widely used in mango cultivation in the semi-arid northeastern Brazil. PBZ remains active in the soil for several years. However, it can severely affect the growth and development of subsequent crops, mainly by reducing vegetative vigor. The aim of this study was to investigate PBZ biodegradation in four samples of soil: P-G (with PBZ application history and with addition of glycerol); NP-G (without PBZ application history and with addition of glycerol); P-NG (with PBZ application history and without addition of glycerol) and NP-NG (without PBZ application history and without addition of glycerol). The biodegradation experiments were carried out in 125 ml flasks containing 10 g soil, at room temperature for 63 days. Mathematical models to analyze the kinetics of degradation of PBZ were applied. PBZ residue was less than 1% in soils with a history, regardless the addition of glycerol. The three models (first-order kinetics, double first-order kinetics and logistic) were well adjusted in these cases (P-G and P-NG). On the other hand, PBZ biodegradation in soil NP-G and NP-NG was 64%, and followed the model of double kinetic. PBZ biodegradation in soil with history was successful, probably because the native microbial had adapted to local environmental conditions. Key words: Paclobutrazol, biodegradation, mathematical models.

Floral biology and Implications for Apple Pollination in Semiarid Northeastern Brazil

Floral biology and Implications for Apple Pollination in Semiarid Northeastern Brazil

Erratum to: The Cultural Value of Invasive Species: A Case Study from Semi–Arid Northeastern Brazil

Erratum to: The Cultural Value of Invasive Species: A Case Study from Semi–Arid Northeastern Brazil

Nutritional status of children and adolescents from a town in the semiarid Northeastern Brazil

ObjectiveTo evaluate the nutritional status of schoolchildren, resident in a semiarid region in the Northeastern Brazil. MethodsThis is a cross-sectional study, involving 860 children and adolescents aged from 5-19 years-old, enrolled in three public schools in the county. The selection of schools was non-probabilistic type and unintentional. The initial population, which integrated the database, was composed by 1,035 children and teenagers, and 175 students (16.9%) were excluded because of inconsistency in the anthropometric data, resulting in a sample of 860 students. The following outcomes were considered: stunting (malnutrition), overweight and obesity (overweight), being the height/age and body mass index/age (BMI/Age), indices respectively used. Children and adolescents with height <-2 standard deviations and overweight and obese weight z score ≥1 were considered stunted. The statistical analysis was descriptive. ResultsThe prevalence of stunting and overweight/obesity was 9.1% and 24.0%, respectively. Overweight and stunting were higher in adolescents aged 15 and over, compared to other age groups analyzed. In relation to gender, malnutrition presented itself in a similar way, but overweight was more frequent among females. ConclusionsThe results revealed that excess weight, here represented by the sum of overweight and obesity, was more prevalent than stunting (malnutrition), highlighting the urgent need for attention to this problem in order to design interventions capable of contributing to the improvement of schoolchildren nutritional status.

2,4-dichlorophenoxyacetic acid as an alternative auxin for rooting of vine rootstock cuttings

Viticulture is an important agricultural activity in semiarid northeastern Brazil, and the quality and ease of vine propagation are very important in this context. This study evaluated the use of 2,4-dichlorophenoxyacetic acid (2,4-D) as an alternative to indolebutyric acid (IBA) in the rooting of vine rootstock cuttings. The trial was conducted at the Universidade Federal de Sergipe (São Cristóvão-SE) between January and March 2010 with cuttings of the rootstocks of 'IAC-766', 'IAC-572', and 'Paulsen 1103' treated with 2,4-D or IBA applied at concentrations of 0, 1000, 2000, or 3000 rng-L-1 for 5 s and planted in a field on washed sand. At 56 days after planting, the percentages of rooted, sprouted, callused, and dead cuttings were evaluated, and also the average number and length of the rooted cuttings. The results showed that 2,4-D was not superior to IBA in the characteristics wanted for the rooting process of the vine rootstock cuttings. The vine rootstocks showed potential for propagation by cutting without auxin application. It was observed that the high concentrations were the worst for the rooting of the cuttings.

The Cultural Value of Invasive Species: A Case Study from Semi–Arid Northeastern Brazil

The Cultural Value of Invasive Species: A Case Study from Semi–Arid Northeastern Brazil. Invasive species are often considered the pariahs of the plant kingdom. In this study, we investigate the utility of native and exotic invasive plants to local residents in a semi–arid area of northeastern Brazil. We address the following questions: Are invasive species considered useful? How are they useful? Are they more or less useful than non–invasive species? Is there a relationship between use categories and taxonomic groups (families, genera, and species)? What plant parts are preferentially used and how are they distributed by categories of usage? And are there differences in the perceived usefulness of native vs. exotic invasive plants? We employed plot sampling of vegetation in anthropogenic habitats. Semi–structured, checklist interviews were carried out with 106 individuals. A total of 56 invasive species were recorded, of which 55 were considered useful. There was no statistical difference in the perceived utility of native vs. exotic invasive species; however, invasive species overall were considered useful more often than non–invasive species. The predominant use was as animal fodder, followed by medicine, food, and technology. Nearly half (44%) of the animal fodder species also served as medicine for people. Herbaceous plants were the most common. Uses varied significantly within taxonomic ranks (species, genus, and family). The most recognized plants were those that are most used locally. This study underscores the value of invasive species in semi–arid Brazil, as well as the need to include local people in regional and national strategies to address invasive species management.

Traditional Ecological Knowledge About Dietary and Reproductive Characteristics of Tupinambis merianae and Hoplias malabaricus in Semiarid Northeastern Brazil

Studies have demonstrated the importance of local ecological knowledge (LEK) in informing our scientific knowledge about how species behave in their environment, and such knowledge can help to guide ecological management decisions. The present study aimed to investigate the relationships between LEK and conventional ecological knowledge based on ethnoecological and ecological information about the diet and reproduction of the tegu lizard (Tupinambis merianae) and the tiger fish (Hoplias malabaricus) in two communities in semiarid northeastern Brazil. Information on the diets of the animals was collected via surveys, and information about reproductive characteristics was obtained from semi-structured interviews with people from two communities. In addition, we analyzed the stomach contents of the animals and performed macroscopic analysis on their gonads. The informants did not report different items for the different ontogenetic stages of the two species under study. However, the information they provided about the diets of the animals did largely match the results of our biological analyses.