995 resultados para clima subtropical


Relevância:

30.00% 30.00%

Publicador:

Resumo:

A fruticultura está presente em todos os estados brasileiros e, como atividade econômica, envolve mais de cinco milhões de pessoas que trabalham de forma direta e indireta no setor. O Brasil é o terceiro maior produtor mundial de frutas, com colheita em torno de 40 milhões de toneladas ao ano, mas participa com apenas 2% do comércio global do setor, o que demonstra o forte consumo interno (ANUÁRIO BRASILEIRO DE FRUTICULTURA, 2010). A área plantada com plantas frutíferas no Brasil está distribuída em 1.034.708 ha com frutas tropicais, 928.552 ha com frutas subtropicais e 151.732 ha com espécies de clima temperado. Dentre as frutas de clima temperado, destaca-se a produção de uvas de mesa e viníferas (81.355 ha); maçãs (38.205 ha); pêssegos, ameixas e nectarinas (19.043 ha); caqui (8.638 ha); morango, amora, framboesa, mirtilo (3.560 ha); figo (2.886 ha); pera (1.394 ha) e marmelo (211 ha). Mesmo com uma área inferior em relação às espécies de clima tropical e subtropical, as frutas de clima temperado têm uma importância socioeconômica destacada em diversas regiões do Brasil, principalmente nos Estados do Rio Grande do Sul, Santa Catarina, Paraná, São Paulo, Minas Gerais e o Vale do São Francisco, seja como cultivo in natura, agroindústria e/ou agroturismo. Para que ocorra a produção de frutas de qualidade nas regiões de clima temperado no Brasil, é necessário o desenvolvimento de programas de melhoramento genético e/ou estudos de manejo e controles sobre a fisiologia das plantas para adaptá-las às condições de inverno ameno e com oscilação de temperaturas, muito frequentes nas principais regiões produtoras brasileiras. Os verões longos e excesso de precipitação ocasionam muitas doenças e pragas, obrigando muitas vezes ao excesso de tratamentos fitossanitários. O manejo dos pomares com a produção integrada de frutas está possibilitando a produção de qualidade e, ao mesmo tempo, reduzindo o impacto ambiental da atividade no setor. Os desafios estão relacionados à adaptação das espécies às mudanças climáticas, à necessidade de se reduzir o uso de agrotóxicos e insumos, aos manejo pré e pós-colheita realizados nas frutas, logística para atender aos diferentes mercados, controle de doenças e pragas e aos programas de melhoramento genético para atender às novas demandas de cada uma das espécies de clima temperado.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This is an observational study of the large-scale moisture transport over South America, with some analyses on its relation to subtropical rainfall. The concept of aerial rivers is proposed as a framework: it is an analogy between the main pathways of moisture flow in the atmosphere and surface rivers. Opposite to surface rivers, aerial rivers gain (lose) water through evaporation (precipitation). The magnitude of the vertically integrated moisture transport is discharge, and precipitable water is like the mass of the liquid column-multiplied by an equivalent speed it gives discharge. Trade wind flow into Amazonia, and the north/northwesterly flow to the subtropics, east of the Andes, are aerial rivers. Aerial lakes are the sections of a moisture pathway where the flow slows down and broadens, because of diffluence, and becomes deeper, with higher precipitable water. This is the case over Amazonia, downstream of the trade wind confluence. In the dry season, moisture from the aerial lake is transported northeastward, but weaker flow over southern Amazonia heads southward toward the subtropics. Southern Amazonia appears as a source of moisture to this flow. Aerial river discharge to the subtropics is comparable to that of the Amazon River. The variations of the amount of moisture coming from Amazonia have an important effect over the variability of discharge. Correlations between the flow from Amazonia and subtropical rainfall are not strong. However, some months within the set of dry seasons observed showed a strong increase (decrease) occurring together with an important increase (decrease) in subtropical rainfall.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Programa de doctorado en Oceanografía

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Nos 5 continentes, o mundo da uva e do vinho concerne mais de 40 países, conforme relatam os dados estatísticos do Office International de la Vigne et du Vin - O.I.V. O Brasil ocupa a 17ª posição no ranking dos produtores mundiais de vinhos (Dutruc-Rosset, 1998). O limite geográfico vitícola do globo, em superfície cultivada, é determinado pela restrição térmica. No Hemisfério Norte os vinhedos comerciais mais setentrionais se encontram ao sul da Inglaterra, ao redor do paralelo 52. No Hemisfério Sul, a viticultura está presente até 39º de latitude, junto à Nova Zelândia. Tonietto (1999), com base no Sistema de Classificação Climática de Peguy (1970), refere a grande diversidade de tipos de clima em que a viticultura mundial é encontrada: Temperado (Oceânico, Oceânico Quente, Temperado de Transição, Continental, Continental Frio), Mediterrâneo, Subtropical (Subtropical, Subtropical Continental), Tropical (Atenuado, Tropical), Semi-Árido (margens dos climas áridos), Árido e Hiperárido. Destaca, ainda, que a maior parte da área vitícola destinada à elaboração de vinho está concentrada em regiões de clima do tipo temperado e do tipo mediterrâneo. A viticultura do Brasil está concentrada em regiões de clima temperado e subtropical (nos dois casos com verões úmidos) e de clima tropical (semi-árido).

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Este trabalho investiga a variabilidade do Sistema de Monções da América do Sul (SMAS) sobre o Brasil com particular interesse na região do cerrado brasileiro. O início, final e total de precipitação durante as monções de verão são examinados utilizando estimativas de precipitação por satélite (pêntadas) do Global Precipitation Climatology Project (GPCP) entre 1979-2004. Analogamente, as características do regime de monção simuladas pelo modelo climático global acoplado MIROC (Model for interdisciplinary Research on Climate) do IPCC (Intergovernmental Panel for Climate Change) são examinadas em dois cenários distintos: o clima do século XX (1981-2000) e o clima em uma condição com o dobro da concentração atual de CO2 (2xCO2) na atmosfera (2061-2080). Mostra-se que a variabilidade espacial do início da monção de verão sobre o cerrado na simulação do clima do século XX pelo MIROC corresponde bem às observações. Além disso, há indicação de uma mudança das caudas da distribuição sazonal da precipitação no Cerrado para um cenário com 2xCO2, comparativamente com o clima presente. Este resultado sugere uma mudança na probabilidade de ocorrência de eventos extremos (secos ou úmidos) em um cenário com 2xCO2 sobre o cerrado, o que de acordo com o MIROC, indica uma maior exposição da região às conseqüências de possíveis mudanças climáticas resultantes do aumento de gases de efeito estufa.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Hydroids are broadly reported in epiphytic associations from different localities showing marked seasonal cycles. Studies have shown that the factors behind these seasonal differences in hydroid richness and abundance may vary significantly according to the area of study. Seasonal differences in epiphytic hydroid cover and richness were evaluated in a Sargassum cymosum C. Agardh bed from Lázaro beach, at Ubatuba, Brazil. Significant seasonal differences were found in total hydroid cover, but not in species richness. Hydroid cover increased from March (early fall) to February (summer). Most of this pattern was caused by two of the most abundant species: Aglaophenia latecarinata Allman, 1877 and Orthopyxis sargassicola (Nutting, 1915). Hydroid richness seems to be related to S. cymosum size but not directly to its biomass. The seasonal differences in hydroid richness and algal cover are shown to be similar to other works in the study region and in the Mediterranean. Seasonal recruitment of hydroid species larvae may be responsible for their seasonal differences in algal cover, although other factors such as grazing activity of gammarid amphipods on S. cymosum must be taken into account.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper provides a description of the wave climate off the Brazilian coast based on an eleven-year time series (Jan/1997-Dec/2007) obtained from the NWW3 operational model hindcast reanalysis. Information about wave climate in Brazilian waters is very scarce and mainly based on occasional short-term observations, the present analysis being the first covering such temporal and spatial scales. To define the wave climate, six sectors were defined and analyzed along the Brazilian shelf-break: South (W1), Southeast (W2), Central (W3), East (W4), Northeast (W5) and North (W6). W1, W2 and W3 wave regimes are determined by the South Atlantic High (SAH) and the passage of synoptic cold fronts; W4, W5 and W6 are controlled by the Intertropical Convergence Zone (ITCZ) and its meridional oscillation. The most energetic waves are from the S, generated by the strong winds associated to the passage of cold fronts, which mainly affect the southern region. Wave power presents a decrease in energy levels from south to north, with its annual variation showing that the winter months are the most energetic in W1 to W4, while in W5 and W6 the most energetic conditions occur during the austral summer. The information presented here provides boundary conditions for studies related to coastal processes, fundamental for a better understanding of the Brazilian coastal zone.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The Community Climate Model (CCM3) from the National Center for Atmospheric Research (NCAR) is used to investigate the effect of the South Atlantic sea surface temperature (SST) anomalies on interannual to decadal variability of South American precipitation. Two ensembles composed of multidecadal simulations forced with monthly SST data from the Hadley Centre for the period 1949 to 2001 are analysed. A statistical treatment based on signal-to-noise ratio and Empirical Orthogonal Functions (EOF) is applied to the ensembles in order to reduce the internal variability among the integrations. The ensemble treatment shows a spatial and temporal dependence of reproducibility. High degree of reproducibility is found in the tropics while the extratropics is apparently less reproducible. Austral autumn (MAM) and spring (SON) precipitation appears to be more reproducible over the South America-South Atlantic region than the summer (DJF) and winter (JJA) rainfall. While the Inter-tropical Convergence Zone (ITCZ) region is dominated by external variance, the South Atlantic Convergence Zone (SACZ) over South America is predominantly determined by internal variance, which makes it a difficult phenomenon to predict. Alternatively, the SACZ over western South Atlantic appears to be more sensitive to the subtropical SST anomalies than over the continent. An attempt is made to separate the atmospheric response forced by the South Atlantic SST anomalies from that associated with the El Nino - Southern Oscillation (ENSO). Results show that both the South Atlantic and Pacific SSTs modulate the intensity and position of the SACZ during DJF. Particularly, the subtropical South Atlantic SSTs are more important than ENSO in determining the position of the SACZ over the southeast Brazilian coast during DJF. On the other hand, the ENSO signal seems to influence the intensity of the SACZ not only in DJF but especially its oceanic branch during MAM. Both local and remote influences, however, are confounded by the large internal variance in the region. During MAM and JJA, the South Atlantic SST anomalies affect the magnitude and the meridional displacement of the ITCZ. In JJA, the ENSO has relatively little influence on the interannual variability of the simulated rainfall. During SON, however, the ENSO seems to counteract the effect of the subtropical South Atlantic SST variations on convection over South America.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Sedentary consumers play an important role on populations of prey and, hence, their patterns of abundance, distribution and coexistence on shores are important to evaluate their potential influence on ecosystem dynamics. Here, we aimed to describe their spatio-temporal distribution and abundance in relation to wave exposure in the intertidal rocky shores of the south-west Atlantic to provide a basis for further understanding of ecological processes in this system. The abundance and composition of the functional groups of sessile organisms and sedentary consumers were taken by sampling the intertidal of sheltered and moderately exposed shores during a period of one year. The sublittoral fringe of sheltered areas was dominated by macroalgae, while the low midlittoral was dominated by bare rock and barnacles. In contrast, filter-feeding animals prevailed at exposed shores, probably explaining the higher abundance of the predator Stramonita haemastoma at these locations. Limpets were more abundant at the midlittoral zone of all shores while sea urchins were exclusively found at the sublittoral fringe of moderately exposed shores, therefore, adding grazing pressure on these areas. The results showed patterns of coexistence, distribution and abundance of those organisms in this subtropical area, presumably as a result of wave action, competition and prey availability. It also brought insights on the influence of top-down and bottom-up processes in this area.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Morphological and molecular analyses have proven to be complementary tools of taxonomic information for the redescription of the ctenostome bryozoans Amathia brasiliensis Busk, 1886 and Amathia distans Busk, 1886. The two species, originally described from material collected by the `Challenger` expedition but synonymized by later authors, now have their status fixed by means of the selection of lectotypes, morphological observations and analyses of DNA sequences described here. The morphological characters allowing the identification of living and/or preserved specimens are (1) A. brasiliensis: whitish-pale pigment spots in the frontal surface of stolons and zooids, and a wide stolon with biserial zooid clusters growing in clockwise and anti-clockwise spirals along it, the spirality direction being maintained from maternal to daughter stolons; and (2) A. distans: bright yellow pigment spots in stolonal and zooidal surfaces including lophophores, and a slender stolon, thickly cuticularized, with biserial zooid clusters growing in clockwise and anti-clockwise spirals along it and the spirality direction not maintained from maternal to daughter stolons. Pairwise comparisons of DNA sequences of the mitochondrial genes cytochrome c oxidase subunit I and large ribosomal RNA subunit revealed deep genetic divergence between A. brasiliensis and A. distans. Finally, analyses of those sequences within a Bayesian phylogenetic context recovered their genealogical species status.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Epilithic biofilm on rocky shores is regulated by physico-chemical and biological factors and is important as a source of food for benthic organisms. The influences of environmental and grazing pressure on spatial variability of biomass of biofilm were evaluated on shores on the north coast of Sao Paulo State (SE Brazil). A general trend of greater abundance of microalgae was observed lower on the shore, but neither of the environmental factors evaluated (wave exposure and shore level) showed consistent effects, and differences were found among specific shores or times (September 2007 and March 2008). The abundance of slow-moving grazers (limpets and littorinids) showed a negative correlation with chlorophyll a concentration on shores. However, experimental exclusion of these grazers failed to show consistent results at small spatial scales. Observations of divergent abundances of the isopod Ligia exotica and biomass of biofilm on isolated boulders on shores led to a short exclusion experiment, where the grazing pressure by L. exotica significantly decreased microalgal biomass. The result suggests that grazing activities of this fast-moving consumer probably mask the influence of slow-moving grazers at small spatial scales, while both have an additive effect at larger scales that masks environmental influences. This is the first evaluation of the impact of the fast-moving herbivore L. exotica on microalgal biomass on rocky shores and opens an interesting discussion about the role of these organisms in subtropical coastal environments.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper describes four new species of the bryozoan genus Beania from the Brazilian coast. Two of them have been previously recorded in the western Atlantic as Beania hirtissima (Heller, 1867) and Beania mirabilis Johnston, 1840, respectively; they are redescribed here as Beania americana n. sp. and Beania mirabilissima n. sp. Two reticulate species, Beania correiae n. sp. and Beania metrii n. sp., are newly described. Descriptions of four other species of Beania from the region are also included: Beania australis Busk, 1852, Beania cupulariensis Osburn, 1914, Beania klugei Cook, 1968 and Beania maxilladentata Ramalho, Muricy & Taylor, 2010.