Semi-arid Northeastern Brazil Research Articles

Obligate association of an oligolectic bee and a seasonal aquatic herb in semi-arid north-eastern Brazil

Hydrocleys martii (Limnocharitaceae) is an annual aquatic herb common in ephemeral isolated ponds in semi-arid northe-astern Brazil. We studied pollination of H. martii, emphasizing reproductive success and association with oligolectic pollinators. The yellow flowers bear a central cone of staminodes that encloses the fertile stamens and four free carpels. The self-incompatible species depends on pollinators to set fruits. In 25 temporary water bodies in five Brazilian states, Protodiscelis palpalis bees (Colletidae, Paracolletinae) were the unique effective pollinators of H. martii and, in 18 of these, the sole flower visitors. Females of this narrowly oligolectic species show adapted behaviour to access the pollen chamber in the flower centre. Females removed more than 80% of the 480 000 pollen grains in only 2 h from the flowers but maintained a high visitation frequency almost until flower senescence. In this highly specialized plant-pollinator system, on average, 1.6% of the pollen grains reached the stigmatic surface and 9.6% remained uncollectible in the flowers. In the absence of P. palpalis, flowers set almost no seeds, indicating reproductive dependence on the oligolectic species. This pioneer pollination study of a species of Limnocharitaceae provides evidence of a close relationship of the family to species of Protodiscelis, their specific pollinators.

Antiproliferative Activity, Antioxidant Capacity and Tannin Content in Plants of Semi-Arid Northeastern Brazil

The objective of this study was to evaluate antiproliferative activity, antioxidant capacity and tannin content in plants from semi-arid northeastern Brazil (Caatinga). For this study, we selected 14 species and we assayed the methanol extracts for antiproliferative activity against the HEp-2 (laryngeal cancer) and NCI-H292 (lung cancer) cell lines using the (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazole) (MTT) method. In addition, the antioxidant activity was evaluated with the DPPH (2,2-diphenyl-2-picrylhydrazyl) assay, and the tannin content was determined by the radial diffusion method. Plants with better antioxidant activity (expressed in a dose able to decrease the initial DPPH concentration by 50%, or IC50) and with higher levels of tannins were: Poincianella pyramidalis (42.95 ± 1.77 µg/mL IC50 and 8.17 ± 0.64 tannin content), Jatropha mollissima (54.09 ± 4.36µg/mL IC50 and 2.35 ± 0.08 tannin content) and Anadenanthera colubrina (73.24 ± 1.47 µg/mL IC50 and 4.41 ± 0.47 tannin content). Plants with enhanced antiproliferative activity (% living cells) were Annona muricata (24.94 ± 0.74 in NCI-H292), Lantana camara (25.8 ± 0.19 in NCI-H292), Handroanthus impetiginosus (41.8 ± 0.47 in NCI-H292) and Mentzelia aspera (45.61 ± 1.94 in HEp-2). For species with better antioxidant and antiproliferative activities, we suggest future in vitro and in vivo comparative studies with other pharmacological models, and to start a process of purification and identification of the possible molecule(s) responsible for the observed pharmacological activity. We believe that the flora of Brazilian semi-arid areas can be a valuable source of plants rich in tannins, cytotoxic compounds and antioxidant agents.

Interação enxerto e porta-enxerto na incidência da resinose do cajueiro

A expansão do cajueiro-anão-precoce no Brasil vem promovendo baixa diversidade genética dos genótipos usados como enxerto e porta-enxerto, ensejando vulnerabilidade da cultura às vicissitudes bióticas como a resinose (Lasiodiplodia theobromae), principal doença do cajueiro no semiárido nordestino. Estima-se que cerca de meio milhão de mudas de cajueiro-anão-precoce sejam produzidas anualmente, sendo a grande maioria delas produzida de propágulos enxertados sobre plântulas oriundas de sementes do clone CCP 06. A principal estratégia de manejo da resinose é o plantio de clones resistentes. Entretanto, entre os aspectos que contribuem para sucessivas epidemias da resinose, destaca-se a falta de estudos de interações genotípicas entre enxerto e porta-enxerto. Este estudo objetivou avaliar o efeito de combinações de clones de cajueiro-anão-precoce usados como enxerto e porta-enxerto na incidência da resinose. Sementes de plantas de polinização aberta de seis clones selecionados foram usadas para produção de porta-enxerto. Os clones comerciais CCP 76 (suscetível) e BRS 226 (resistente) foram usados como enxertos. O experimento foi realizado obedecendo ao delineamento de blocos ao acaso, no esquema fatorial 2 x 6, com quatro repetições e nove plantas por parcela do tipo quadrada, sob condições de elevada pressão da doença, em Pio IX-PI. Três anos após o plantio definitivo, a incidência (I) e a severidade (S) (escala de 0 a 4) da resinose foram superiores no clone CCP 76 (I = 97% e S=2,10) em relação ao BRS 226 (I = 33% e S=0,36), independentemente do porta-enxerto. O clone CP 06 como porta-enxerto foi o único que reduziu a incidência e a severidade da resinose, independentemente do genótipo do enxerto. Este clone foi capaz de reduzir a severidade da resinose do clone CCP 76 (S=2,10) como enxerto em quase 30%.

“Return” and Extension Actions After Ethnobotanical Research: The Perceptions and Expectations of a Rural Community in Semi-arid Northeastern Brazil

The scientific community has debated the importance of “return” activities after ethnobiological studies. This issue has provoked debate because it touches on the ethics of research and the relationships with the people involved in these studies. This case study aimed to investigate community perception of an ethnobotany research project that was carried out in the semi-arid region of northeastern Brazil. Furthermore, we reported how the residents of this rural community felt about participating in the activities of “return” that arose from the projects. Our findings demonstrate that “return” activities should be planned from the design phase of the research until its closure as a lifelong process that allows the communities involved to gradually take ownership of the information and actions that are being generated. Similarly, we argue that such activities must be negotiated with the people of the community so that they have decision-making power and autonomy to decide what is most relevant to their lives.

Medicinal plants with bioprospecting potential used in semi-arid northeastern Brazil

Objectives Many species of the Caatinga flora are used as medicines in local communities. In recent decades, the knowledge and use of these species has been expanding within this region. We attempted to record the local diversity of medicinal plants used to treat various diseases in a rural community in the state of Ceará, Brazil, and to evaluate the promising medicinal species for bioprospecting studies. Methods An ethnobotanical survey was conducted using free list and semi-structured interviews. To indicate medicinal plants that stood out, the relative importance (RI) of species mentioned by key-informants (20), by general informants in the community (71) and by all informants (91), was analyzed. The group of species that stood out for human body systems based on the informant consensus factor (ICF) was also evaluated. Results A total of 119 species were recorded that were associated with 92 health problems. Of these species, 100 were cited by key-informants and 86 were cited by general informants. Nineteen species showed a great versatility of use, including the following: Myracrodruon urundeuva Allemão, Bauhinia cheilanta (Bong.) Steud., Hymenaea courbaril L., Mentha x villosa Huds ., Ziziphus joazeiro Mart., and Ruta graveolens L . Key-informants cited 33 exclusive species, from which nine presented greater relative importance. General informants cited 19 exclusive species, 2 with greatest relative importance. The therapeutic properties were grouped into 16 body system categories. These grouping categories included skin diseases and diseases of the subcutaneous tissue; sensory system (ears) disorders; respiratory disorders; and injuries, poisoning and other external symptoms. Conclusion The great diversity of medicinal plants used in the community is evident. Some species had both high relative importance and high consensus factors among the informants; these particular species are recommended for bioprospecting studies.

Relationship of air and soil temperature with the amount of chlorophyll a and b in Jurema preta (Mimosa tenuiflora(Willd.) Poiret) in semi-arid northeastern Brazil

A comunidade cientifica tem-se preocupado mais com Caatinga (Savana Estepica), seja em funcao da degradacao antropica e/ou devido a grande vulnerabilidade as mudancas climaticas. Considerando a abundância da jurema preta na regiao semiarida, a sua importância economica e ecologica, e o estado de degradacao provocado pela pecuaria em que se encontram muitas areas de Caatinga, e ainda levando em consideracao as mudancas climaticas, neste estudo pretende-se relacionar fatores internos da folha (pigmentos) com fatores externos (temperatura do ar) da jurema preta (Mimosa tenuiflora (Willd) Poiret) de regiao semiarida do Nordeste do Brasil. Neste estudo, foram aplicadas estatisticas descritivas e de correlacao linear para relacionar os fatores interno e externos a folha. Os resultados nao apresentaram grandes diferencas entre a relacao da temperatura do ar e da temperatura do solo com as clorofilas a e b. Essas informacoes poderao servir como base inicial aos estudos do balanco energetico e a quantidade de clorofila que podera ser encontrada na especie estudada (dominante no semi-arido). Estudos futuros poderao indicar um modelo que apresente uma relacao entre a quantidade de clorofila, conhecendo-se a quantidade de energia que a planta recebe (temperatura do ar).

Opuntia Forage Production Systems: Status and Prospects for Rangeland Application

This paper reports recent findings in Opuntia genetics, nutrient fertilization, and cultivation with promise to overcome limitations for Opuntia-based forage production systems. The essentially spineless, fast-growing Opuntia ficus-indica (L.) Mill. has been planted on millions of hectares for forage in tropical areas of Brazil and North Africa. The spiny, cold-hardy Opuntia species have been used for forage in Mexico and the southwestern United States, after the cladodes have been chopped or singed to remove the spines. Due to the recent increases in fuel prices, burning of the spines is more costly. Where only spiny varieties exist, some range animals forage on them without manipulation. As a result, spines frequently penetrate and form lesions on mouth and esophageal tissues, leading to serious health issues. Slow growth and low protein (ca. 5%) of the native Opuntia spiny species on nonfertilized rangeland is an impediment to greater use of Opuntia for forage. The only spineless species adaptable to US Department of Agriculture cold hardiness zones , 8 (i.e., Opuntia ellisiana Griffiths) is relatively slow growing. Full sibling crosses indicate spine heritability is probably single-gene controlled. Interspecific hybrids between the frost-sensitive, fast-growing, and spineless O. ficus-indica with cold-hardy, spiny, slower-growing O. lindheimerii Engelm. have produced spineless progeny, with greater cold hardiness than O. ficus-indica, and greater productivity than cold-hardy, spineless O. ellisiana. Nitrogen limitations on water-use efficiency of Opuntia have been overcome for the 120 million ha of semiarid northeastern Brazil with added nitrogen and phosphorus fertilization. With control of competing vegetation and fertilization, this system has 40 t dry matter ? ha 21 of 9.2% crude protein forage with 600 mm rainfall in 16 mo. Opuntia ficus-indica plantations were profitable even though a duplication of fertilizer current prices was considered.

Reproductive seasonality of the fish fauna and limnoecology of semi-arid Brazilian reservoirs

The native fish fauna commonly found in the drainage basins of rivers and reservoirs of Latin America, including those of the semi-arid Northeastern Brazil, are representatives of the Neotropical region. This work reports on the reproductive ecology of five commercially important and consumable native fish species, in relation to rainfall and hydrological variables of the semi-arid reservoirs in Brazil. Pluviometric precipitation, temperature, pH, dissolved oxygen and electrical conductivity of the water were registered, and maturation of fish gonads was assessed on a monthly basis. This region is characterized with short spells of rain interspersed with long dry season and rainfall seems to be the main environmental factor which modulates the timing of the spawning period of fish. Construction of reservoirs without adequate facilities for fish migration has an adverse impact on the migratory fish species which are of commercial and ecological importance to semi-arid Northeastern Brazil.

ELISA protein G for the diagnosis of contagious agalactia in small ruminants

An indirect enzyme-linked immunosorbent assay utilizing total antigen (ELISA-Gt) and sonicated (ELISA-Gs) of Mycoplasma agalactiae protein G was standardized for the detection of anti- M. agalactiae antibodies in goats. Eighty-six serum samples obtained from infected and uninfected flocks were used to evaluate the tests. The relative sensitivity of the ELISA-Gt and ELISA-Gs was 77.27% and 88.63%, respectively, while both had 95.24% of specificity. A survey of antibodies against contagious agalactia (CA) in 317 goats in Cariri microrregion, Semi-arid northeastern Brazil was undertaken by indirect ELISA-Gs, and 264 animals (83.28%) were positive. Considering the inexistence of vaccines against CA in Brazil, the high prevalence detected suggests the presence of intensive infection between caprine flocks in the microrregion.

Ciclagem de nutrientes via precipitação pluvial total, interna e escoamento pelo tronco em sistema agroflorestal com Gliricidia sepium

A deposição de nutrientes contidos na água de chuva que passa pela copa das árvores e que escoa pelo tronco até o solo pode constituir uma via importante da ciclagem biogeoquímica em sistemas agroflorestais de baixo uso de insumos externos. Todavia, não há informação disponível sobre esses processos em agroecossistemas da região semi-árida do Nordeste brasileiro. O presente trabalho foi conduzido em um sistema agroflorestal de cultivo em aléias, com gliricídia e milho, em Esperança, PB, e teve como objetivo quantificar: a proporção da água de chuva que escoa através da copa das árvores, ou pelo tronco, ou que é interceptada pela copa; e as entradas de N, P e K contidos na água escoada através da copa ou pelo tronco, bem como na água de chuva em áreas sem árvores. Na área experimental, foram delimitadas quatro parcelas, onde foram instalados coletores a 0,50 m de distância do tronco das árvores de gliricídia e coletores tipo ´colarinho´ acoplados ao redor do tronco destas. Paralelamente, foram instalados coletores em áreas adjacentes, sem árvores, para quantificação da precipitação pluvial total. Da precipitação pluvial total, 67 % escoou através da copa , 0,74 % escoou pelo tronco e 32 % foi interceptada pela copa das árvores. As concentrações de N e P foram similares nas amostras da água escoada através da copa ou pelo tronco, porém estas foram cerca de 300 % maiores do que na água de chuva. A concentração de K na água escoada pelo tronco foi cerca de 100 e 600 % maior do que na água escoada através da copa e na água de chuva, respectivamente. Em média, os aportes de N, P e K ao solo foram de 5, 1 e 24 kg ha-1 na água de chuva; 9, 2 e 62 kg ha-1 na água escoada através da copa; e 0,12, 0,02 e 1 kg ha-1 na água escoada pelo tronco, respectivamente. Os resultados demonstram a importância da adoção de sistemas agroflorestais para a sustentabilidade de sistemas agrícolas de baixo uso de insumos externos, como os da região semi-árida do Nordeste.

Microbiota fúngica de Melipona subnitida Ducke (Hymenoptera: Apidae)

This paper reports on the occurrence of filamentous fungi found on the surface of the bees body from the specie Melipona subnitida Ducke that inhabits rocky places on the semi-arid Northeastern Brazil. Bees with cause of natural death were collected of beehives belonging to the Centro de Multiplicação de Animais Silvestres of the Universidade Federal Rural do Semi-Arido. We found the fungi: Aspergillus sp. 6 (37.5%); Aspergillus niger 2 (12.5%); Penicilium sp. 2 (12.5%); Aspergillus terreus 1 (6.3%); Curvularia sp. 1 (6.35%); Monilia sp. 1 (6.3%); Nigrospora sp. 1 (6.3%); Cladosporium sp. 1 (6.3%); Tricoderma sp. 1 (6.3%).

The response of zooplankton assemblages to variations in the water quality of four man-made lakes in semi-arid northeastern Brazil

The response of zooplankton assemblages to variations in the water quality of four man-made lakes, caused by eutrophication and siltation, was investigated by means of canonical correspon- dence analysis. Monte Carlo simulations using the CCA eigenvalues as test statistics revealed that changes in zooplankton species composition along the environmental gradients of trophic state and abiogenic turbidity were highly significant. Brachionus calyciflorus, Thermocyclops sp. and Argyrodiaptomus sp. were good indicators of eutrophic conditions, whereas B. dolabratus, Keratella tropica and Hexarthra mira were good indicators of high turbidity due to suspended sediments. Overall, our results showed that changes in the water quality of man-made lakes in a tropical semi-arid region have significant effects on the structure of zooplankton assemblages that can poten- tially affect the functioning of these ecosystems.

AMPHIBIAN DNA SHOWS MARKED GENETIC STRUCTURE AND TRACKS PLEISTOCENE CLIMATE CHANGE IN NORTHEASTERN BRAZIL

The glacial refugia paradigm has been broadly applied to patterns of species dynamics and population diversification. However, recent geological studies have demonstrated striking Pleistocene climate changes in currently semiarid northeastern Brazil at time intervals much more frequent than the climatic oscillations associated with glacial and interglacial periods. These geomorphic data documented recurrent pulses of wet regimes in the past 210,000 years that correlate with climate anomalies affecting multiple continents. While analyzing DNA sequences of two mitochondrial genes (cytochrome b and NADH-dehydrogenase subunit 2) and one nuclear marker (cellular-myelocytomatosis proto-oncogene) in the forest-associated frogs Proceratophrys boiei and Ischnocnema gr. ramagii, we found evidence of biological responses consistent with these pluvial maxima events. Sampled areas included old, naturally isolated forest enclaves within the semiarid Caatinga, as well as recent man-made fragments of humid coastal Atlantic forest. Results show that mtDNA lineages in enclave populations are monophyletic or nearly so, whereas nonenclave populations are polyphyletic and more diverse. The studied taxa show evidence of demographic expansions at times that match phases of pluvial maxima inferred from geological data. Divergence times between several populations fall within comparatively drier intervals suggested by geomorphology. Mitochondrial and nuclear data show local populations to be genetically structured, with some high levels of differentiation that suggest the need of further taxonomic work.

Toward a South America Land Data Assimilation System: Aspects of land surface model spin‐up using the Simplified Simple Biosphere

This paper describes a spin‐up experiment conducted over South America using the Simplified Simple Biosphere (SSiB) land surface model to study the process of model adjustment to atmospheric forcing data. The experiment was carried out as a precursor to the use of SSiB in a South American Land Data Assimilation System (SALDAS). The results from an 11 year long recursive simulation using three different initial conditions of soil wetness (control, wet and dry) are examined. The control run was initiated by interpolation of the NCEP/DOE Global Reanalysis‐2 (NCEP/DOE R‐2) soil moisture data set. In each case the time required for the model to reach equilibrium was calculated. The wet initialization leads to a faster adjustment of the soil moisture field, followed by the control and then the dry initialization. Overall, the final spin‐up states using the SSiB‐based SALDAS are generally wetter than both the NCEP/DOE R‐2 and the Centro de Previsao do Tempo e Estudos Climaticos (CPTEC–Brazilian Center for Weather Forecast and Climate Studies) operational initial soil moisture states, consequently modeled latent heat is higher and sensible heat lower in the final year of simulation when compared with the first year. Selected regions, i.e., in semiarid northeastern Brazil, the transition zone to the south of the Amazon tropical forest, and the central Andes were studied in more detail because they took longer to spin up (up to 56 months) when compared with other areas (less than 24 months). It is shown that there is a rapid change in the soil moisture in all layers in the first 2 months of simulation followed by a subsequent slow and steady adjustment: This could imply there are increasing errors in medium range simulations. Spin‐up is longest where frozen soil is present for long periods such as in the central Andes.

Distribuição de fósforo em diferentes ordens de solo do semi-árido da Paraíba e de Pernambuco

Os solos do semi-árido nordestino têm sido reconhecidos como deficientes em P. Todavia, a grande diversidade de ordens a que eles pertencem indica que não devem ser semelhantes quanto às concentrações das diferentes formas deste elemento. A concentração de P foi avaliada em 69 amostras de solo das dez ordens mais comuns no semi-árido, nas camadas de 0-20 e 20-40 cm. O P foi extraído pelo Mehlich-1 e por fracionamento seqüencial, por extração com resina, NaHCO3, NaOH e H2SO4, e por digestão peróxido/sulfúrica. O P total (somatório das frações) variou de 52 a 1.625 mg kg-1, estando a maioria dos solos na faixa entre 100 e 200 mg kg-1, na camada de 0-20 cm, com uma grande variabilidade entre as ordens e dentro delas. Grande variabilidade foi encontrada também para qualquer das frações. De modo geral, Neossolos Flúvicos, Vertissolos, Luvissolos e Cambissolos tiveram os maiores valores; Argissolos, Neossolos Litólicos e Latossolos, valores intermediários, e Neossolos Regolíticos, Planossolos e Neossolos Quartzarênicos, os mais baixos. O maior reservatório de P, de forma geral, foi o P residual e os menores, as frações mais lábeis (P resina e Pi-NaHCO3), representando juntas entre 7 e 12 % do P total. Mehlich-1 extraiu baixas proporções de P total dos Vertissolos (1 %) e alta proporção dos Latossolos (24 %), o inverso ocorrendo com a extração com bicarbonato (11 e 5 %, respectivamente). A resina extraiu baixas proporções em todas as ordens (1 a 6 %).

Integrated modelling of climate, water, soil, agricultural and socio-economic processes: A general introduction of the methodology and some exemplary results from the semi-arid north-east of Brazil

Many semi-arid regions are characterised by water scarcity and vulnerability of natural resources, pronounced climatic variability and social stress. Integrated studies including climatology, hydrology, and socio-economic studies are required both for analysing the dynamic natural conditions and to assess possible strategies to make semi-arid regions less vulnerable to the present and changing climate. The model introduced here dynamically describes the relationships between climate forcing, water availability, agriculture and selected societal processes. The model has been tailored to simulate the rather complex situation in the semi-arid north-eastern Brazil in a quantitative manner including the sensitivity to external forcing, such as climate change. The selected results presented show the general functioning of the integrated model, with a primary focus on climate change impacts. It becomes evident that due to large differences in regional climate scenarios, it is still impossible to give quantitative values for the most probable development, e.g., to assign probabilities to the simulated results. However, it becomes clear that water is a very crucial factor, and that an efficient and ecologically sound water management is a key question for the further development of that semi-arid region. The simulation results show that, independent of the differences in climate change scenarios, rain-fed farming is more vulnerable to drought impacts compared to irrigated farming. However, the capacity of irrigation and other water infrastructure systems to enhance resilience in respect to climatic fluctuations is significantly constrained given a significant negative precipitation trend.

Quaternary ecological and geomorphic changes associated with rainfall events in presently semi‐arid northeastern Brazil

AbstractSeveral geomorphic features and palaeobiotic remains in now semi‐arid northeastern Brazil indicate major palaeoenvironmental changes during past periods of increased rainfall. 230Th mass spectrometric ages of speleothems and travertines have allowed the determination of the timing and duration of wetter than present conditions. The data demonstrate that wet events have occurred throughout much of the Pleistocene, present dry conditions having been established at the end of the Younger Dryas. A markedly different fauna comprising megafaunal elements not adapted to the present low arboreal scrubland caatinga vegetation existed in the area. Palaeobotanical remains embedded in travertine indicate forested vegetation at these wetter intervals, suggesting that the caatinga was then replaced or mixed with a semi‐deciduous forest. Due to the abundance of travertine sites containing fossil botanical remains in northeastern Brazil, it is believed that forest expansion occurred over large areas of the now semi‐arid zone, showing that the long hypothesised forested links between biodiversity‐rich Amazon and Atlantic rainforests may indeed have existed during these moister phases. Copyright © 2004 John Wiley & Sons, Ltd.

Modeling soil nutrient limitations to crop production in semiarid NE of Brazil with a modified EPIC version: I. Changes in the source code of the model

A series of modifications for the source code of EPIC version 0160 in order to simulate growth, yield, and nutrient uptake by the crops under the pedo-climatic conditions of the semiarid Northeastern Brazil are presented. The modifications included changes in chemical properties of the soil due to liming as manual option, changes in the estimation of soil Al saturation, effects of Na on the soil physical properties, interaction between climatic and nutrient constraints to crop growth, modifications in the estimation of labile P factor for uptake and in the calculations of the N and P stress factors which are now estimated as a function of the ratio between the daily uptake and daily demand for the potential growth. Moreover, the structure of a simple soil and plant K model designed to be incorporated into EPIC is described. The model maintains pools of exchangeable, soluble and fixed K for the mineral form in the soil; of crop residue K for the organic form and of grain, stover and root K for the crop form. The model runs on a daily time step, simulating K uptake by the crops and transformations between the different soil pools as well as several other processes like leaching, runoff, lateral subsurface flow, movement upward through soil evaporation, K recycling from crop residues and the effect of limited soil K availability on crop development. The model is sensitive to soil chemical and physical properties, crop K requirements, crop competition, tillage practices, fertilizer rate, and soil water content. In a second paper of this series, the test of the proposed modifications, including the plant and soil potassium sub-model, for simulations of crop growth, yield and nutrient uptake of a maize × cowpea intercrop in the semiarid NE of Brazil is presented.

Water Scarcity Under Scenarios for Global Climate Change and Regional Development in Semiarid Northeastern Brazil

The state of Ceará, located in semiarid northeastern Brazil, suffers under irregularly recurring droughts that go along with water scarcity. Structural policies to control and reduce water scarcity, as water supply and demand management, should be seen as long-term planning, and thus must consider climate change and regional development. To this end, the present research proposes a model-based global change scenario. Water stress is assessed for 184 municipalities in Ceará between 2001 and 2025. For this purpose, four global change scenarios are developed, considering both global climate change and the effects of development policies. Climatic, hydrological, and water use models are applied and a proposed index computed for identification of long-term water stress. Application of the methodology in the focus area shows that, if no effective intervention measures are taken, up to almost 60 percent of the municipalities of the state may suffer under long-term water scarcity by 2025. On average, municipalities in the state of Ceará have a water shortage probability for the next 25 years ranging from 9 percent to 20 percent annually, depending on the scenario. The 10 percent most stressed municipalities have a probability of over 80 percent annually of facing water scarcity in the scenario period (25 years). Results also show that a decentralized development policy can compensate for the possible severe effects of climatic trends on future water availability over the scenario period.

Plantas visitadas por Centris spp. (Hymenoptera: Apidae) na Caatinga para obtenção de recursos florais

É apresentada uma revisão dos registros de plantas visitadas por espécies de abelhas do gênero Centris em áreas de caatinga, vegetação xerófila predominante na região semi-árida do nordeste do Brasil, incluindo dados de literatura e resultados originais de seis levantamentos anuais da fauna de abelhas e flora melitófila de áreas restritas, realizados nos estados da Paraíba, Bahia e Rio Grande do Norte. Nos levantamentos realizados foi registrado um total de 21 espécies de Centris, sendo observada a maior riqueza de espécies em Castro Alves e Itatim (Bahia), 12 e 10 espécies, respectivamente. É sugerido que a presença de elementos de biomas contíguos seja determinante para o maior número de espécies observado, uma vez que essas duas localidades encontram-se próximas ao limite leste da Caatinga. Foram registradas 69 espécies de plantas visitadas. Dentre as fontes de néctar, Caesalpinia pyramidalis (Caesalpiniaceae) e Melochia tomentosa (Sterculiaceae) destacam-se pelo número de espécies de Centris visitantes e pelo número de áreas onde foram encontradas. Espécies de Chamaecrista e Senna (Caesalpiniaceae) e de Solanum (Solanaceae) parecem ser importantes fontes de pólen. Chamaecrista nictitans e C. pascuorum são registradas pela primeira vez como fontes de pólen de Centris hyptidis. As fontes de óleo registradas na Caatinga para Centris pertencem às famílias Malpighiaceae e Scrophulariaceae. Dentre as espécies de Centris mais coletadas, as de distribuição não restrita à Caatinga (C. fuscata, C. aenea, C. tarsata e C. trigonoides) apresentam maior sobreposição no espectro de plantas visitadas, do que a observada em relação a C. hyptidis, espécie endêmica.