First Record of Culex (Culex) brethesi (Dyar) (Diptera: Culicidae) in Rio Grande do Sul State, Brazil

This is the first record of Culex (Culex) brethesi (Dyar) in Rio Grande do Sul state, Brazil. The species was identified from specimens collected in a sand bar vegetation with the aid of a Nasci's trap, during an expedition for surveillance of the West Nile Virus in July of 2006, in the city of Mostardas, Rio Grande do Sul, Brazil.

PLANT ACCUMULATIONS ALONG THE ITANHAEM RIVER BASIN, SOUTHERN COAST OF SAO PAULO STATE, BRAZIL

Examination of the mechanisms involved in the construction of present-day vegetative deposits along coastal waterways has made it possible to establish depositional patterns that can be compared with those found in similar environments in geologic time. These patterns include not only the composition and transport of the debris but also an estimation of the time involved in its deposition. Six sites with active deposits of plant macrodebris in the coastal basin of the Itanhaem River, Sao Paulo State, Brazil, were used in the study. In the central portion of the basin, the interior coastal plain is covered with restinga forest (dense, wet tropical forest of low altitudes), while the lower portion consists of mangrove swamps. The coast reflects anthropogenic intervention, and only a few scattered remnants of precolonization dune vegetation remain. The results after three years of study suggest that the accumulation of plant macrodebris in the middle and lower portions of the basin is parautochthonous, since only the leaves of genera typical of the restinga forest and mangrove swamp, respectively, were found. Along the coast the accumulations involved a mixture of parautochthonous and allochthonous elements. On the levee of the Branco River and within the mangrove swamp, deposition was slow, and many of the elements decayed quickly; such accumulations show little potential for preservation and eventual fossilization. A different site, however, reveals the rapid deposition of thick layers of plant debris, presumably associated with storms, and these accumulations are preserved for long periods, constituting good candidates for possible fossilization.

Nitrogen availability patterns in white-sand vegetations of Central Brazilian Amazon

Addressing spatial variability in nitrogen (N) availability in the Central Brazilian Amazon, we hypothesized that N availability varies among white-sand vegetation types (campina and campinarana) and lowland tropical forests (dense terra-firme forests) in the Central Brazilian Amazon, under the same climate conditions. Accordingly, we measured soil and foliar N concentration and N isotope ratios (delta(15)N) throughout the campina-campinarana transect and compared to published dense terra-firme forest results. There were no differences between white-sand vegetation types in regard to soil N concentration, C:N ratio and delta(15)N across the transect. Both white-sand vegetation types showed very low foliar N concentrations and elevated foliar C:N ratios, and no significant difference between site types was observed. Foliar delta(15)N was depleted, varying from -9.6 to 1.6aEuro degrees in the white-sand vegetations. The legume Aldina heterophylla had the highest average delta(15)N values (-1.5aEuro degrees) as well as the highest foliar N concentration (2.1%) while the non-legume species had more depleted delta(15)N values and the average foliar N concentrations varied from 0.9 to 1.5% among them. Despite the high variation in foliar delta(15)N among plants, a significant and gradual (15)N-enrichment in foliar isotopic signatures throughout the campina-campinarana transect was observed. Individual plants growing in the campinarana were significantly enriched in (15)N compared to those in campina. In the white-sand N-limited ecosystems, the differentiation of N use seems to be a major cause of variations observed in foliar delta(15)N values throughout the campina-campinarana transect.

Isotopic view of vegetation and carbon and nitrogen cycles in a cerrado ecosystem, southeastern Brazil

Carbon and nitrogen biogeochemical cycles in savannas are strongly regulated by the seasonal distribution of precipitation and pulses of nutrients released during the wetting of the dry soil and are critical to the dynamics of microorganisms and vegetation. The objective of this study was to investigate the spatial and temporal variability of C and N isotope ratios as indicators of the cycling of these elements in a cerrado sensu stricto area, within a protected area in a State Park in the state of São Paulo, Brazil. The foliar δ13C and δ15N values varied from -33.6 to -24.4 ‰ and -2.5 to 4.5 ‰, respectively. The δ13C values showed a consistent relationship with canopy height, revealing the importance of structure of the canopy over the C isotopic signature of the vegetation. Carbon isotopic variations associated with the length of the dry season indicated the importance of recent fixed C to the integrated isotopic signature of the leaf organic C. The studied Cerrado species showed a depleted foliar δ15N, but a wide range of foliar Nitrogen with no difference among canopy heights. However, seasonal variability was observed, with foliar δ15N values being higher in the transition period between dry and rainy seasons. The variation of the foliar C and N isotope ratios presented here was consistent with highly diverse vegetation with high energy available but low availability of water and N.

Influence of soil properties on the abundance of plant species in ferruginous rocky soils vegetation, southeastern Brazil

Ferruginous "campos rupestres" are a particular type of vegetation growing on iron-rich primary soils. We investigated the influence of soil properties on plant species abundance at two sites of ferruginous "campos rupestres" and one site of quartzitic "campo rupestre", all of them in "Quadrilátero Ferrífero", in Minas Gerais State, southeastern Brazil. In each site, 30 quadrats were sampled to assess plant species composition and abundance, and soil samples were taken to perform chemical and physical analyses. The analyzed soils are strongly acidic and presented low fertility and high levels of metallic cations; a principal component analysis of soil data showed a clear segregation among sites due mainly to fertility and heavy metals content, especially Cu, Zn, and Pb. The canonical correspondence analysis indicated a strong correlation between plant species abundance and soil properties, also segregating the sites.

A new species of sand-dwelling catfish, with a phylogenetic diagnosis of Pygidianops Myers (Siluriformes: Trichomycteridae: Glanapteryginae)

A new species of sand-dwelling catfish genus Pygidianops, P. amphioxus, is described from the Negro and lower Amazon basins. The new species differs from its three congeners in the elongate eel-like body, the short barbels, and the small caudal fin, continuous with the body, among other traits of internal anatomy. The absence of anal fin further distinguishes P. amphioxus from all other Pygidianops species except P. magoi and the presence of eyes from all except P. cuao. The new Pygidianops seems to be the sister species to P. magoi, the two species sharing a unique mesethmoid with a dorsally-bent tip lacking cornua, and a produced articular process in the palatine for the articulation with the neurocranium. Pygidianops amphioxus is a permanent and highly-specialized inhabitant of psammic environments. Additional characters are proposed as synapomorphies of Pygidianops, including a hypertrophied symphyseal joint and associated ligament in the lower jaw; an elongate, laterally-directed, process on the dorsal surface of the premaxilla; and a rotated lower jaw, where the surface normally facing laterally in other glanapterygines is instead directed ventrally. These and other characters are incorporated into a revised phylogenetic diagnosis of Pygidianops.

Sand fly captures with Disney traps in area of occurrence of Leishmania (Leishmania) amazonensis in the state of Mato Grosso do Sul, mid-western Brazil

INTRODUCTION: The work was conducted to study phlebotomine fauna (Diptera: Psychodidae) and aspects of American cutaneous leishmaniasis transmission in a forested area where Leishmania (Leishmania) amazonensis occurs, situated in the municipality of Bela Vista, State of Mato Grosso do Sul, Brazil. METHODS: The captures were conducted with modified Disney traps, using hamster (Mesocricetus auratus) as bait, from May 2004 to January 2006. RESULTS: Ten species of phlebotomine sandflies were captured: Brumptomyia avellari, Brumptomyia brumpti, Bichromomyia flaviscutellata, Evandromyia bourrouli, Evandromyia lenti, Lutzomyia longipalpis, Psathyromyia campograndensis, Psathyromyia punctigeniculata, Psathyromyia shannoni and Sciopemyia sordellii. The two predominant species were Ev bourrouli (57.3%) and Bi flaviscutellata (41.4%), present at all sampling sites. Two of the 36 hamsters used as bait presented natural infection with Leishmania. The parasite was identified as Leishmania (Leishmania) amazonensis. CONCLUSIONS: Analysis of the results revealed the efficiency of Disney traps for capturing Bichromomyia flaviscutellata and the simultaneous presence of both vector and the Leishmania species transmitted by the same can be considered a predictive factor of the occurrence of leishmaniasis outbreaks for the human population that occupies the location.

Variabilidade espacial da textura de um Argissolo Vermelho Amarelo sob cultivo de pastagem e vegetação nativa

O conhecimento da variabilidade espacial dos atributos de um solo sob diferentes coberturas auxilia o estudo das alterações ocorridas em razão do manejo. O objetivo deste trabalho foi determinar, com uso da estatística clássica e geoestatística, a variabilidade espacial das frações texturais de um solo cultivado com pastagem e vegetação nativa. Amostras de solo foram coletadas na profundidade de 0-0,20m, nos pontos de cruzamento de uma malha, com intervalos regulares de 10m, totalizando 64 pontos em cada área. Na área de pastagem, as frações areia grossa e total apresentaram valores médios maiores em relação à vegetação nativa e correlações negativas com as altitudes dos pontos amostrais nas duas áreas. Todas as frações texturais apresentaram dependência espacial de moderada a alta nas duas áreas e com o patamar definido, com exceção da areia fina e do silte na pastagem. Grande parte dessa variabilidade ocorre em função da erosão hídrica.

Carbon Stocks and Isotopic Composition of the Organic Matter in Soils Covered by Native Vegetation and Pasture in Sorocaba, SP, Brazil

Land cover change constitutes one of main way of alteration of soil organic matter in both quantitative and qualitative terms. The goal of this study was to compare the carbon stock and the isotopic signature of the organic matter in the soil of areas with different land use,covered with forest and grass (pasture). The study area is located at Sorocaba, SP, Brazil. Using un-deformed soil samples, we measured the carbon content and bulk density. The isotopic signature of soil carbon was determined through the analysis of isotopic ratio (12)C/(13)C. The pasture soil stocks 48% less carbon than the soil covered by natural forest. The isotopic signature indicated that 42.2% of organic matter of the soil covered by pasture is originated from grasses. This characterizes a highly degradation of organic matter in the environment, both quantitatively and qualitatively. Hence, some guidelines of recuperation are described in order to restore the soil organic matter, structure and porosity.

Late Pleistocene and Holocene vegetation changes in northeastern Brazil determined from carbon isotopes and charcoal records in soils

Northeastern Brazil represents a strategic area in terms of Quaternary records of environmental changes in South America due to its distinct semi-arid climate in near equatorial latitudes. In this study, carbon isotope and charcoal distribution records in soils are used to characterize vegetation dynamics, forest fires and their relation to climate change since the Late Pleistocene in the States of Ceara, Piaui and Paraiba, Northeastern Brazil. At the Ceara site, the carbon isotope record showed an enrichment trend from -24%(o) to 19%(o) during the early-mid Holocene, indicating an opening of vegetation and expansion of savanna vegetation (C(4) plants) during this period. A trend toward more depleted delta(13)C values (similar to-32%.) in the late Holocene indicates an expansion of forest vegetation (C(3) plants). A similar trend is observed at the Piaui and Paraiba sites where values of similar to-24%0 are associated with open forest vegetation during the late Pleistocene. In the early-mid Holocene, delta(13)C values of up to -18.0%(o), suggest the expansion of C4 plants. Based on the carbon isotope data, it is postulated that from similar to 18,000 cal yr B.P. to similar to 11,800 cal yr B.P.-similar to 10,000 cal yr B.P. arboreal vegetation was dominant in northeastern Brazil and is associated with humid climates. The savanna expanded from similar to 10,000 cal yr B.P. to similar to 4500-3200 cal yr B.P. due to a less humid/drier climatic phase, also supported by the significant presence of fires (charcoal fragments in the soil). From approximately 3200-2000 cal yr B.P. to the present, carbon isotope records suggest forest expansion and a more humid phase. These results form part of a regional pattern since they are in agreement with paleovegetation records obtained in regions of Maranhao, northeastern Brazil and in the Amazon and Rondonia States, northern Brazil. (C) 2010 Elsevier B.V. All rights reserved.

Last glacial maximum (LGM) vegetation changes in the Atlantic Forest, southeastern Brazil

This study was carried out in a continental Atlantic Forest located in the southern region of Sao Paulo State, southeastern Brazil. The aim of the study was to evaluate the vegetation dynamics in similar to 70 km forest ecosystem transect that occurred during the late Pleistocene and Holocene in this region, using the stable carbon isotopes (delta C-13) analysis on soil organic matter (SOM) and the C-14 dating of buried charcoal fragments and the humin fraction of SOM. The isotope data (delta C-13) of SOM in the deeper horizons, indicating the presence of more open vegetation than the present, with a probable mixture of C-3 and C-4 plants, suggesting the presence of a drier climate in the period of similar to 20 ka to similar to 16-14 ka BP. From similar to 16 to 14 ka BP to the present, a significant predominance Of C3 plants was observed, indicating an expansion of the forest, probably associated with the presence of a more humid climate than the previous period. The results indicated the presence of open vegetation during the late glacial, probably associated with a drier period, also observed in other regions of Brazil. The Atlantic Forest ecosystem seems to have developed at least since the early Holocene in Southeastern Brazil. (c) 2007 Elsevier Ltd and INQUA. All rights reserved.

Relationship between installation torque and uplift capacity of deep helical piles in sand

Le facteur empirique de correlation du torque K(T), qui represente la capacite de soulevement du torque d`installation de pieux helicoidaux, est generalement utilise comme instrument de controle de la qualite sur le terrain pour ce type de fondations. Dans cet article, une relation theorique entre la capacite de soulevement et le torque d`installation de pieux helicoidaux places profondement dans du sable est presentee. Un programme experimental, qui comprend des essais centrifuge et de cisaillement direct a l`interface, a ete effectue dans le but de valider cette relation theorique. Les resultats experimentaux ont ete compares aux resultats predits par l`approche suggeree, et les resultats montrent une bonne concordance. Puisque le modele developpe depend de l`angle de friction residuel a l`interface delta(r) entre la surface de l`helice du pieu et le sable, les resultats de delta(r) obtenus a partir de differents echantillons de sable sont presentes afin d`etre utilises lors de l`application sur le terrain de la relation theorique proposee. De plus, les valeurs de K(T) obtenues dans ces travaux ont ete comparees a celles reportees dans la litterature; celles-ci ayant ete obtenues lors d`essais sur le terrain et en laboratoire sur des pieux helicoidaux dans le sable. Cette analyse a permis de demontrer que les valeurs mesurees de K(T) diminuent lorsque la dimension des pieux augmente, ainsi qu`avec une augmentation de l`angle de friction du sable, dans la plupart des cas. Ces derniers resultats ont aussi ete demontres avec le modele presente.

Failure Mechanisms in Sand over a Deep Active Trapdoor

An experimental testing program was undertaken to investigate failure mechanisms induced by the active movement of a deep rectangular trapdoor underlying a granular soil. Reduced-scale models were tested under normal gravity as well as under an increased gravitational field using a centrifuge facility. Some models were used to evaluate the performance of both flexible and rigid pipes undergoing a localized loss of support. Failure mechanisms in the longitudinal direction of the models were characterized by a single, well-defined failure surface that developed within the limits of the trapdoor. However, failure mechanisms in the transverse direction of the models were characterized by multiple failure surfaces extending outside the limits of the trapdoor. Significant dilation of the soil located immediately above the trapdoor was identified in the failure of the models. The pattern of the failure mechanisms was found to be affected by the stress level and backfill density. Higher stress levels were found to lead to well-developed failure zones. The influence of backfill density was found to be more relevant in models involving flexible pipes. Pipes embedded within loose backfill were severely damaged after loss of support, while pipes embedded in dense backfill experienced negligible deformations. These results indicate that damage to pipelines caused by ground loss of support can be significantly minimized by controlling the compaction of the fill.

Sand bioconsolidation through the precipitation of calcium carbonate by two ureolytic bacteria

Two ureolytic strains, B. sphaericus LMG 22257 and Bacillus sp (I-001), were tested for their ability to consolidate sand by submitting them to two days` treatment using 10(7) viable cell concentrations of inocula and medium precipitation with calcium ions. The results showed that B. sphaericus LMG 22257 induced greater calcium carbonate formation. Both strains produced calcite and were able to consolidate sand. Tensile strength of consolidated sand was not a function of the amount of precipitated CaCO(3) but a linear function of the ratio bioconsolidation index (BC) defined as the ratio of CaCO(3) volume to initial sand porosity. A simple model to estimate the engineering benefits of consolidation is proposed. (C) 2011 Elsevier B.V. All rights reserved.