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Frações de nitrogênio em Luvissolo sob sistemas agroflorestais e convencional no semi-árido cearense; Nitrogen fractions in a Luvisol under agroforestry and conventional systems in the semi-arid zone of Ceará, Brazil

MAIA, Stoécio Malta Ferreira; XAVIER, Francisco Alisson da Silva; OLIVEIRA, Teógenes Senna de; MENDONÇA, Eduardo de Sá; ARAÚJO FILHO, João Ambrósio
Fonte: Sociedade Brasileira de Ciência do Solo Publicador: Sociedade Brasileira de Ciência do Solo
Tipo: Artigo de Revista Científica
POR
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Os sistemas agroflorestais têm sido amplamente promovidos como sistemas de produção agrícola sustentáveis, principalmente para regiões subdesenvolvidas, onde o uso de insumos externos é inviável. Este trabalho objetivou avaliar o impacto de quatro sistemas agroflorestais e um sistema convencional sobre os teores de N total, mineral e em diferentes frações orgânicas, após cinco anos de uso de um Luvissolo na região semi-árida cearense, em experimento instalado na Embrapa Caprinos, em Sobral (CE). Os sistemas testados foram: agrossilvipastoril (AGP); silvipastoril (SILV); tradicional cultivado em 1998 e 1999 (TR98); tradicional cultivado em 2002 (TR02); cultivo convencional (CC); e uma área de Caatinga (CA). Nas amostras de solo, avaliaram-se os teores de N total, N-NH4+, N-NO3-, N microbiano, N da matéria orgânica leve (livre e oclusa) e o N das substâncias húmicas. Os resultados indicaram que todos os tratamentos condicionaram elevados teores de N-NO3-, representando entre 10,3 e 23,5 % dos teores de N total. O sistema CC reduziu os teores de N total e das frações das substâncias húmicas em 38 e 44 %, respectivamente, na camada superficial do solo. Dentre os sistemas agroflorestais, os sistemas AGP e TR98 causaram redução significativa dos teores de N total...

Latent heat loss of dairy cows in an equatorial semi-arid environment

da Silva, Roberto Gomes; Campos Maia, Alex Sandro; de Macedo Costa, Leonardo Lelis; Fernandes de Queiroz, Joao Paulo A.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 927-932
ENG
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); The present study aimed to evaluate evaporative heat transfer of dairy cows bred in a hot semi-arid environment. Cutaneous (E (S)) and respiratory (E (R)) evaporation were measured (810 observations) in 177 purebred and crossbred Holstein cows from five herds located in the equatorial semi-arid region, and one herd in the subtropical region of Brazil. Rectal temperature (T (R)), hair coat surface temperature (T (S)) and respiratory rate (F (R)) were also measured. Observations were made in the subtropical region from August to December, and in the semi-arid region from April to July. Measurements were done from 1100 to 1600 hours, after cows remained in a pen exposed to the sun. Environmental variables measured in the same locations as the animals were black globe temperature (T (G)), air temperature (T (A)), wind speed (U), and partial air vapour pressure (P (V)). Data were analysed by mixed models, using the least squares method. Results showed that average E (S) and E (R) were higher in the semi-arid region (117.2 W m(-2) and 44.0 W m(-2), respectively) than in the subtropical region (85.2 W m(-2) and 30.2 W m(-2), respectively). Herds and individual cows were significant effects (P < 0.01) for all traits in the semi-arid region. Body parts did not affect T (S) and E (S) in the subtropical region...

Outcrop Groundwater Prospecting, Drilling, and Well Construction in Hard Rocks in Semi-arid Regions

Chambel, António
Fonte: CRC Press, Taylor & Francis Group/Balkema Publicador: CRC Press, Taylor & Francis Group/Balkema
Tipo: Parte de Livro
ENG
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This chapter presents some recommendations for prospecting, drilling and well construction in hard rocks in semi-arid regions. Considering that these conditions are present in many countries where technology is not always available, the chapter concentrates on the most basic and simple methods to plan where best to drill and maximize success through the direct observation of rock types, weathering and fracturing. The advantage for the geologist and hydrogeologist in an arid or semi-arid environment is that vegetation is normally scarce and the weathering layer thin, allowing a direct view of the rock in circumstances impossible in other climate regions of the world. The close observation of the weathering material, and especially of the fracture network, mainly the fracture density, dip, extension and interconnection, can provide important information for a field hydrogeologist who can then plan the best place for drilling. The most appropriate drilling technique, if available in the area, is rotary percussion, also designated as down-the-hole drilling, with drilling rates that can achieve 100 m per day in normal circumstances. This allows a well to be constructed in about two days, essential in the case of disaster relief. Finally...

Pandemic influenza A (H1N1) 2009: epidemiological analysis of cases in a tropical/semi-arid region of Brazil

Pires Neto,Roberto da Justa; Lemos,Daniele Rocha Queiroz; Cavalcanti,Luciano Pamplona de Góes; Ramos Junior,Alberto Novaes; Alencar,Carlos Henrique; Façanha,Mônica Cardoso; Barroso,Madalena Isabel Coelho; Vilar,Dina Cortez Lima Feitosa; Fonseca Neto,Ma
Fonte: Sociedade Brasileira de Medicina Tropical - SBMT Publicador: Sociedade Brasileira de Medicina Tropical - SBMT
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2013 EN
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Introduction The year 2009 marked the beginning of a pandemic caused by a new variant of influenza A (H1N1). After spreading through North America, the pandemic influenza virus (H1N1) 2009 spread rapidly throughout the world. The aim of this study was to describe the clinical and epidemiological characteristics of cases of pandemic influenza in a tropical/semi-arid region of Brazil. Methods A retrospective study analyzed all suspected cases of pandemic influenza (H1N1) 2009 reported in the Ceará State through the National Information System for Notifiable Diseases during the pandemic period between 28 April, 2009 and November 25, 2010. Results A total of 616 suspected cases were notified, 58 (9.4%) in the containment phase and 558 (90.6%) in the mitigation phase. Most cases were of affected young people resident in the City of Fortaleza, the largest urban center in the State of Ceará. The most frequent symptoms presented by the cases with confirmed infection were fever, cough, myalgia, arthralgia, and nasal congestion. Mortality rate was 0.0009/1,000 inhabitants and lethality was 5.6%. Deaths were observed only in the mitigation phase. Mortality rates were similar for both sexes but were higher in the age group under 5 years. Conclusions The study suggests that the influenza A (H1N1) pandemic in this tropical/semi-arid region had a lower magnitude when compared to states in the Southern and Southeastern regions of Brazil.

Influence of tree species on the herbaceous understory and soil chemical characteristics in a silvopastoral system in semi-arid northeastern Brazil

Menezes,R. S. C.; Salcedo,I. H.
Fonte: Sociedade Brasileira de Ciência do Solo Publicador: Sociedade Brasileira de Ciência do Solo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/1999 EN
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66.53%
Studies from some semi-arid regions of the world have shown the beneficial effect of trees in silvopastoral systems, by promoting the formation of resource islands and increasing the sustainability of the system. No data are available in this respect for tree species of common occurrence in semi-arid Northeastern Brazil. In the present study, conducted in the summer of 1996, three tree species (Zyziphus joazeiro, Spondias tuberosa and Prosopis juliflora: ) found within Cenchrus ciliaris pastures were selected to evaluate differences on herbaceous understory and soil chemical characteristics between samples taken under the tree canopy and in open grass areas. Transects extending from the tree trunk to open grass areas were established, and soil (0-15 cm) and herbaceous understory (standing live biomass in 1 m² plots) samples were taken at 0, 25, 50, 100, 150 and 200% of the average canopy radius (average radius was 6.6 ± 0.5, 4.5 ± 0.5, and 5.3 ± 0.8 m for Z. joazeiro, P. juliflora, and S. tuberosa , respectively). Higher levels of soil C, N, P, Ca, Mg, K, and Na were found under the canopies of Z. joazeiro and P. juliflora: trees, as compared to open grass areas. Only soil Mg organic P were higher under the canopies of S. tuberosa trees...

Effects of fishing technique on assessing species composition in aquatic systems in semi-arid Brazil

Medeiros,ESF; Silva,MJ; Figueiredo,BRS; Ramos,TPA; Ramos,RTC
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2010 EN
Relevância na Pesquisa
66.6%
In most ecological field research, appropriate sampling is critical for the understanding of processes underlying fish populations and communities, and is even more important in heterogeneous environments such as the aquatic systems of the semi-arid region of Brazil. This study intends to make a contribution to the development of sampling programs and gear selection in aquatic systems of semi-arid Brazil by evaluating the effects of different fishing techniques on the assessment of richness and composition of the fish fauna in selected aquatic environments. Six sites were selected to represent typical artificial (reservoirs) and natural (intermittent streams) environments and four different types of sampling gear were applied to each site during four occasions. The present study shows that when selecting sampling techniques to be used in aquatic systems in semi-arid Brazil, one must consider the objectives of the study, e.g. ecological or taxonomic, in order to decide on inclusion of rare species in the sampling population. Also, the effect of the sampling gear on natural abundances of fish must be considered given that some sampling techniques are highly detrimental to fish population numbers.

Aquatic systems in semi-arid Brazil: limnology and management

Barbosa,José Etham de Lucena; Medeiros,Elvio Sérgio Figueredo; Brasil,Jandeson; Cordeiro,Raquel da Silva; Crispim,Maria Cristina Basilio; Silva,Gustavo Henrique Gonzaga da
Fonte: Associação Brasileira de Limnologia Publicador: Associação Brasileira de Limnologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2012 EN
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Aquatic systems in semi-arid Brazil include natural shallow lakes, artificial reservoirs and intermittent streams and rivers. These systems are distinctive features in the semi-arid landscape and comprise a range of associated systems functioning as an ever-changing mosaic of dry/wet patches. Lakes and reservoirs in semi-arid Brazil are subject to important periods of water shortages, whereas rivers and streams are characterized as highly variable and driven by the extremes of water flow and its absence. Within this view a catchment-scale approach must be used to create a holistic model to conceptualize and comprehend these aquatic systems, since the aquatic environment types in the semi-arid region of Brazil incorporate broader aspects within the catchment scale such as geomorphology, vegetation, climate and land use. This paper summarizes some of the information on the aquatic systems of the Brazilian semi-arid region and shows the importance of limnological studies in this region. It also attempts to establish perspectives for future research considering the catchment as a scale for surveying biological processes and limnological characteristics of the various aquatic systems. It is presented information on their overall structure and functioning...

Avaliação da produção de sedimentos em áreas de diferentes escalas na bacia experimental doriacho Gravatá, semi-árido alagoano.; Evaluation of the sediment yield in different scales in the experimental basin of Gravatá river, semi-arid regions of the State of Alagoas.

Falcão, Sebastião Coelho Marinho
Fonte: Universidade Federal de Alagoas; BR; Recursos Hídricos e Saneamento; Programa de Pós-Graduação em Recursos Hídricos e Saneamento; UFAL Publicador: Universidade Federal de Alagoas; BR; Recursos Hídricos e Saneamento; Programa de Pós-Graduação em Recursos Hídricos e Saneamento; UFAL
Tipo: Dissertação Formato: application/pdf
POR
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The current water resource management in the Brazilian Semi-arid area is scarce in information on methods that seek the optimization of the use of its water, which is fundamentally important having in view the serious panorama experienced in relation to the water availability. Searching to explore and understand the behavior of hydrosedimentology variables in the semi-arid region is increasingly common the study in experimental basins. In this context, this paper presents the instrumentation of an experimental basin in the semi-arid regions of the State of Alagoas, with emphasis on hydrosedimentology monitoring processes. This study was entirety developed from subsidies from hydrosedimentology monitoring processes in the field, having as the general objective to quantify the production of sediments in two different scales of experimental units: plots and microbasin. The selected microbasin has contributing area of 0.183 ha, and an average declivity of 6.5% and being constructed in the outlet a sediment pit for collecting the superficial discharge. In another area, three plots were installed, with 3 m² each, in a land with average declivity of 13%. The monitoring in the plots happened as of simulated rainfall, the simulator being calibrated to produce heavy rain for each of the plots. In relation to soil cover...

Aspects of nutrient cycling in semi arid mallee and mulga communities

Burrows, William Henry
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Thesis (PhD); Doctor of Philosophy (PhD)
EN_AU
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A study was made of nutrient distribution and fluxes in mallee and mulga ecosystems to obtain an appreciation of the manner in which the woody plants have adapted to their infertile semi arid habitats. Emphasis was placed in utilisation and fluxes of nitrogen and phosphorus within these ecosystems. Pool sizes of total phosphorus, ‘available’ phosphorus and total nitrogen within the communities exhibited remarkable similarities despite wide differences in geographical location and plant assemblages supported. There was a pronounced concentration of organic carbon, total nitrogen and ‘available’ phosphorus in the soil surface horizons. High resilience within mallee communities was demonstrated by comparison of a fifteen year old regrowth community with an adjacent mature (c. 55 year old) stand. There were only small differences between both communities in nitrogen and phosphorus pool size in the vegetation, and in the lignotuber biomass, leaf area index and the amount of leaf litter present on the soil surface. The above ground net primary productivity of the regrowth community (5406 kg/ha/yr) was more than twice that of the mature mallee (2379 kg/ha/yr). The mulga community had high concentrations of nitrogen in both its living and dead tissues compared with mallee. This suggested that the Acacia/ Rhizobium symbiosis was effective but there was apparently no build-up of total nitrogen within the soil profile. There were considerable fluctuations in the pulses of litter and nutrients onto the floors of these woodland ecosystems. However litter fall from Eucalyptus spp. exhibited a distinct summer maximum whereas litter fall in mulga appeared to be largely independent of season and rainfall. Withdrawal of nitrogen and phosphorus prior to leaf abscission indicated conservation in the use of these elements. There were striking similarities in the breakdown and decomposition rates of mallee and mulga leaves...

Fire in arid and semi-arid Australia: 1998-2004.

Turner, Dorothy
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2009
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66.75%
Fire is a crucial element in shaping our world, whether caused naturally by lightning or by humans, either accidentally or on purpose. These fires can have both positive and negative consequences and impacts on our natural environment, human health, society and its economics, and global climate through carbon emissions. In arid and semi-arid Australia (70% of the continent), individual fires frequently exceed 1 million hectares, and have collectively burnt up to 9% of this total area in a single year. Stakeholders all have different outlooks and priorities about these phenomena. Little objective information about the fire regime and its drivers has been available for this vast area with its very low population density, with previous analyses limited in spatial and/or temporal extent. This lack of knowledge has hampered attempts at effective management. Satellite imagery enables active fires to be detected as fire hotspots, and burnt areas to be mapped as patches from the change of surface reflectance properties in successive images. The National Oceanographic and Atmospheric Administration’s (NOAA) Advanced Very High Resolution Radiometer (AVHRR) imagery has recently been used to map both fire hotspots (FHS) and fire affected areas (FAA) for the entire Australian continent dating back to 1998. In this dissertation...

Acacia victoriae and its association with sugary-exudate producing herbivorous insects and trailing dominant ants in semi-arid Australia.

Weichel, Nyree
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2012
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66.57%
Associations between ants, sap-sucking herbivores, and plants are often mutualistic, but abiotic and biotic conditions can change the magnitude of costs and benefits to partners. This is sometimes sufficient to tip the outcome for at least one partner to neutral or negative. Little is understood about this conditionality of outcomes. Other arthropods on the plants are likely to affect outcomes for partners, but little is known about broader effects of these associations on the arthropod community. Consistent differences in environmental conditions might bring about differences in function of these associations, so there may be a tendency for outcomes for partners to depend on biome, for which there is some evidence. Associations where plants provide sugary exudate (SE) to ants either directly or through supporting populations of herbivorous insects are widespread and common in Australia on the two most common genera Acacia and Eucalyptus, yet very few studies of this have been done. Due to the unique suite of environmental conditions on the Austral continent such as the prevalence of aridity, these types of associations may be particularly adaptive for woody plants. Acacia victoriae is the second most widespread acacia in Australia. A membracid of a genus which is widely distributed across Australia...

Zooplankton assemblages in eutrophic reservoirs of the Brazilian semi-arid

Eskinazi-Sant'Anna,EM.; Menezes,R.; Costa,IS.; Araújo,M.; Panosso,R.; Attayde,JL.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2013 EN
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66.53%
Species composition, density, and temporal dynamics of zooplankton were studied in six reservoirs in a semi-arid region in tropical northeastern Brazil (Rio Grande do Norte state). All the reservoirs are highly eutrophic, with high contents of total nitrogen (minimum of 1200 µg.L-1) and total phosphorus (minimum of 10 µg.L-1), and extremely high algal biomass was registered (surpassing 20 µg Chl a.L-1). All the reservoirs showed an enduring condition of high turbidity and phytoplankton assemblages dominated by cyanobacteria. Zooplankton also showed quantitative patterns suggestive of eutrophic conditions, expressed by high densities, mainly in Passagem das Traíras and Sabugi reservoirs. A spatial differentiation in the composition of the zooplankton community was registered. Rotifers (especially Keratella tropica, Brachionus havanensis, and Keratella americana) were the dominant forms in the zooplankton community of Itans, Passagem das Traíras, and Sabugi reservoirs, while calanoid copepods (mainly Notodiaptomus cearensis) dominated in the Armando Ribeiro, Gargalheiras, and Parelhas systems. The existence of novel relationships in zooplankton community composition in eutrophic reservoirs in this tropical semi-arid region must be considered in designating zooplankton indicators of eutrophic conditions.

The long-term effects of the management of a forest soil on its carbon content, microbial biomass and activity under a semi-arid climate

Bastida, F.; Moreno, J. L.; Hernández Fernández Muñoz, María Teresa; García Izquierdo, Carlos
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 190855 bytes; application/pdf
ENG
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10 pages, 2 figures, 5 tables.; Terracing of soil is a reforestation practice well established in South-eastern Spain (semi-arid climate), because it increases plant growth by means of run-off reduction. This is a crucial factor because in this zone the climatic conditions (especially the scarce rainfall) impede plant development. In this work, the influence in the long-term (13 years) of two types of physical management (terracing and strip planting) in the reforestation of a mountainside with Pinus halepensis Millar, together with the addition of an organic amendment (produced from municipal refuse), was evaluated by means of different biochemical and microbiological parameters, including those related to the size and general activity of microbial populations, such as microbial biomass C (MBC), basal respiration, ATP, dehydrogenase activity and hydrolase activities. Also, the study of labile C fractions (water-soluble C, WSC) provided information regarding the metabolic potential of the soil microorganisms. Three-way ANOVA showed that organic amendment significantly increased general microbial activity and carbon fractions. Strips produced, in the long-term, only a slightly positive effect on the microbial activity. The results indicate that terracing...

Antioxidant enzyme activities in shoots from three mycorrhizal shrub species afforested in a degraded semi-arid soil

Alguacil García, María del Mar; Hernández, José Antonio; Caravaca Ballester, María Fuensanta; Portillo, B.; Roldán Garrigos, Antonio
Fonte: John Wiley & Sons Publicador: John Wiley & Sons
Tipo: Artículo Formato: 579917 bytes; image/jpeg
ENG
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66.6%
Mycorrhizae may help plants to thrive in Mediterranean semi-arid ecosystems by altering antioxidant enzyme activities. Our objective was to determine the influence of mycorrhizal inoculation with an allochthonous arbuscular mycorrhizal (AM) fungus, Glomus claroideum, Schenck & Smith, or with a mixture of native AM fungi, on the activity of antioxidant enzymes from shoots of Olea europaea L. ssp. sylvestris, Retama sphaerocarpa (L.) Boissier and Rhamnus lycioides L. seedlings afforested in a degraded Mediterranean semi-arid soil. One year after planting, shoot biomass of inoculated O. europaea seedlings was about 630%, of non-inoculated plants. Shoot biomass of G. claroideum-colonized R. sphaerocarpa was greater than that of seedlings inoculated with the mixed native AM fungi after 12 months. Inoculation with a mix of native AM fungi was the most effective treatment for increasing shoot biomass and N, P and K contents in shoot tissues of R. lycioides. Both mycorrhizal inoculation treatments increased the nutrient contents in shoots of O. europaea and R. lycioides. In O. europaea plants, the inoculation treatments increased catalase, ascorbate peroxidase and dehydroascorbate reductase activities, but not monodehydroascorbate reductase and glutathione reductase activities. Inoculation with G. claroideum increased the activities of all antioxidant enzymes in R. sphaerocarpa. Monodehydroascorbate reductase...

Aggregating spatial heterogeneity in a bush vegetation patch in semi-arid SE Spain: A multi-layer model versus a single-layer model

Were, Ana M.; Villagarcía, Luis; Domingo, Francisco; Moro, María J.; Dolman, A. J.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 472075 bytes; application/pdf
ENG
Relevância na Pesquisa
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12 pages, 5 figures.-- Printed version published on Jan 2008.; In semi-arid areas, where vegetation is sparse and clumped, models used to estimate evapotranspiration (λE) consider soil and plants as different sources of evaporation. When working at higher scales of heterogeneity, the modelling of surface fluxes introduces effective parameters that enclose the sub-grid heterogeneity. In this work we used both approaches to estimate the λE of a sparse-vegetation patch of Retama sphaerocarpa (L.) Boiss in a semi-arid area in southeast Spain. Firstly, we used a multi-layer model considering plant, soil under plant and bare soil, each with its own surface and aerodynamic resistances and available energy, interacting at a within canopy height. Secondly, we used a single-layer model that uses the effective surface and aerodynamic resistances of the patch, calculated by different aggregations of the soil and plant resistances considered in the multi-layer model. The estimates of λE were compared with measured values obtained by an Eddy covariance system. Results show that the use of effective surface resistances aggregated in parallel and effective aerodynamic resistances aggregated in series in a single-layer model produced similar estimates of λE as a multi-layer model. When compared to the measured values...

“Coping With Drought”: A Contribution of the Semi-Arid Articulation/ASA for Sustainable Development; “Conviver com a seca”: contribuição da Articulação do Semi-Árido/ASA para o desenvolvimento sustentável

Duque, Ghislaine; UFCG
Fonte: UFPR Publicador: UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; Formato: application/pdf
Publicado em 06/06/2008 POR
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A região semi-árida do Brasil coloca imensos desafios para o desenvolvimento sustentável: as característicasedafo-climáticas, sem dúvida, mas, muito mais, a preponderância de uma política baseada, de umlado, nos princípios da revolução verde e no incentivo ao agronegócio, e, do outro, no assistencialismopara os pobres do campo. Contra o paradigma da “luta contra a seca”, concretizada pela construção degrandes reservatórios de água, sua distribuição por carro pipa – gerador de dependência – e seu uso parairrigação – causando danos ao meio ambiente, os agricultores familiares e suas entidades, organizadosna Articulação do Semi-Árido/ASA, reclamam-se do princípio da “convivência com a seca”. Resgatame divulgam experiências nascidas do saber popular, aprimoradas no diálogo com o saber científico, etransformam as mesmas em referências para propor ao poder público um modelo diferente de políticaspúblicas. Assim nasceu o Programa de Formação e Mobilização para Convivência no Semi-Árido:um Milhão de Cisternas Rurais (P1MC)...

First record of Chantransia macrospora Wood, 1887 (Batrachospermales, Rhodophyta) in semi-arid northeastern Brazil; Primeiro registro de Chantransia macrospora Wood, 1887 (Batrachospermales, Rhodophyta) no semiárido do nordeste do Brasil

Vasconcelos, Janiele França; Universidade Estadual de Maringá; Barbosa, José Etham Lucena; Universidade Estadual da Paraíba; Moura, Gustavo Correia; Universidade Estadual da Paraíba; Azevedo, Daniele Jovem Silva; Universidade Estadual da Paraíba; Az
Fonte: Universidade Federal de Santa Catarina Publicador: Universidade Federal de Santa Catarina
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Formato: application/pdf
Publicado em 20/08/2014 ENG
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66.53%
http://dx.doi.org/10.5007/2175-7925.2014v27n4p129This study presents the first record of Chantransia macrospora in the state of Rio Grande do Norte, in the semi-arid region of northeastern Brazil. Analyses of periphytic algae revealed C. macrospora individuals associated in particular with shells of Melanoides tuberculatus, a non-native species, suggesting that C. macrospora have been introduced into systems associated with the gastropods. In this context, new records of C. macrospora are still expected for the Brazilian semi-arid region in the next years.; http://dx.doi.org/10.5007/2175-7925.2014v27n4p129Este trabalho apresenta o primeiro registro de Chantransia macrospora do estado do Rio Grande do Norte na região do semiárido no nordeste do Brasil. Análises das algas perifíticas revelaram indivíduos de C. macrospora associados especialmente com conchas de Melanoides tuberculatus, uma espécie exótica, sugerindo que C. macrospora tenha sido introduzida nestes sistemas associados com o gastrópode. Neste contexto, novos registros de C. macrospora ainda são esperados para a região semiárida do Brasil nos próximos anos.

Estratégias de Gestão da Água em Situação de Escassez: Regiões Semiáridas e Mediterrânicas; Water management strategies in a scarcity situation: Semi-arid and Mediterranean regions

Rosado, Joana; Universidade de Évora; Morais, Maria Manuela; Universidade de Évora
Fonte: Editora de Livros IABS Publicador: Editora de Livros IABS
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; Formato: application/pdf
Publicado em 22/12/2010 POR
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66.63%
No início do século XXI a escassez da água é inquestionável constituindo uma ameaça para a humanidade e para a biosfera. Esta situação é sentida nas regiões Áridas, Semiáridas e Mediterrânicas. A gestão dos recursos aquáticos e da disponibilidade de água é um tema complexo e de uma enorme importância estratégica para o desenvolvimento sustentável. O principal objectivo deste trabalho é apresentar e discutir estratégias de gestão da água em regiões Semiáridas e Mediterrânicas através da revisão da literatura disponível. Conclui-se que as regiões Semiáridas, devido às suas características específicas, sofrerão mais com a escassez. Relativamente ao Mediterrâneo, todos os cenários de evolução futura prevêem uma diminuição da precipitação, tendência que trará graves impactes em termos sociais e ambientais. Interessará às regiões Mediterrânicas implementar as técnicas simples e de baixo custo utilizadas nas regiões Semiáridas, muitas das quais presentemente abandonadas mas com tradições centenárias na história do Mediterrâneo.; At the beginning of the 21st century, the shortage of water is unquestionable constituting a threat to humanity and the biosphere. This situation is experienced in arid...

Characteristics of local groundwater recharge cycles in South African semi-arid hard rock terrains: Rainfall-groundwater interaction

van Wyk,E; van Tonder,GJ; Vermeulen,D
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
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The semi-arid and arid regions occupy almost two-thirds of South Africa and fall in the winter and summer rainfall zones of the sub-continent. The annual rainfall patterns can be regarded as intermittent with a significant spatial variability due to the unique winter/summer synoptic systems manifesting over Southern Africa. Summer rainfall events indicate that episodic wet periods, consisting of up to 8 consecutive days, may contain falls that contribute to almost 45% to 60% of the total annual rainfall of an area; associated with relatively higher rain rates (1.5 to 10 mmh-1). Hyetograph-hydrograph time-series data sets, however, indicate that episodic rainfall events are responsible for rapid, but sustainable groundwater recharge events. The recurrence rate of these events in the semi-arid and arid regions is still low and aquifer storage-recharge is therefore not an annual event. The recharge flow path through the unsaturated zone reservoir plays an important role in the underdrainage flow pattern, and subsequently the saturated flow regime. It resembles a simple L-shaped flow path driven by direct recharge mounding in the fractured hard rock terrain and indirect recharge to the surrounding sub-reservoirs. The lag-times between rainfall events and water table responses were found to be significantly short; a matter of a few hours to less than a few days. Evidence of multi-modal...

Modelling the long-term consequences of undernutrition of cows grazing semi-arid range for the growth of their progeny

Richardson,F.D.
Fonte: South African Journal of Animal Science Publicador: South African Journal of Animal Science
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 EN
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Undernutrition of cows grazing semi-arid range as a result of drought or heavy stocking rates reduces prenatal and pre-weaning growth of their calves. A mechanistic model has been developed that simulates the productivity of vegetation and cattle on semi-arid savanna rangeland in southern Africa. When cows are stocked at 0.200 cows/ha instead of 0.123 cows/ha the model predicted that empty body weights of their progeny at birth and weaning would be reduced by 2.9 and 43.8 kg, respectively. If all young animals are stocked at 0.22 animals/ha after weaning, differences in empty body weight at weaning are predicted to persist almost unchanged for a further two years. The model also predicted that undernutrition of cattle aged 21 months would be followed by partial compensatory growth. Comparison of simulated results with data from experiments in Zimbabwe indicates that the model realistically simulates the effects of stocking rate on cattle growth.