327 research outputs found

    Distribuição da Savana (Cerrado) no Pantanal brasileiro: uma análise quantitativa.

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    A Savana (Cerrado) é uma formação forística com predominância de gramíneas, árvores esparsas e arbustos isolados ou em pequenos grupos, situadas principalmente em áreas de transição entre bosques e prados, presentes em regiões de clima tropical com estação seca. O objetivo deste trabalho é identifcar o conjunto de vegetação de Savana encontrada no Pantanal brasileiro, buscando compreender, espacialmente, a distribuição dessa vegetação no ambiente pantaneiro. Para isso, foram utilizados dois diferentes limites do Pantanal (planície e Bioma) e o mapa da vegetação do Pantanal na escala 1:250.000; foi utilizado como ferramenta de auxílio para verifcação da distribuição do cerrado na área estudada, o Sistema de Informação Georreferenciada ? Spring. A análise da distribuição demonstrou que o Cerrado ocorre em todo o Pantanal, exceto no Sul, nas sub-regiões Nabileque e Porto Murtinho. Além disso, quatro classes de cerrado representam aproximadamente 65% da formação total da área de análise. Foram elaborados dois mapas do Pantanal, demonstrando a distribuição deste tipo de vegetação de acordo com os limites da planície e do Bioma, além da quantifcação das áreas cobertas por cada ftofsionomia mapeada.Geopantanal 2010

    Identificação de padrões de imagens LANDSAT no período de seca e cheia para interpretação de Savana Estépica (Chaco) e seus contatos florísticos no Pantanal.

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    Este trabalho tem como objetivo identificar e comparar informações de diversas fitofisionomias observadas, nos períodos de seca e cheia, em áreas do Pantanal ocupadas por Savana Estépica(Chaco) e seus contatos florísticos e, estabelecer padrões para interpretação de imagens Landsat.SBSR 2011

    Quantificação da cobertura vegetal e uso da terra da bacia hidrográfica do rio Miranda/MS.

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    Resumo. O intenso uso da terra, principalmente a pecuária, vem alertando órgãos governamentais e estudiosos quanto às alterações da cobertura vegetal do estado do Mato Grosso do Sul (MS). Técnicas de sensoriamento remoto têm auxiliado trabalhos de gerenciamento ambiental de extensas áreas, disponibilizando produtos e informações quase em tempo real para apoio à tomada de decisão de órgãos públicos e privados. Visando auxiliar projetos de proteção e gerenciamento ambiental do MS o trabalho tem como objetivo quantificar os tipos de cobertura vegetal e uso da terra da bacia hidrográfica do rio Miranda (BHRM) e associá-los as classes de declividade. Para isso utilizou-se mapeamentos já existentes na escala 1:100.000. Os dados de uso da terra, cobertura vegetal e declividade foram recortados para a área da BHRM, mosaicados, para posteriormente realizar-se a quantificação do uso e cobertura e associá-los com as classes de declividade pelo método da tabulação cruzada. O resultado demonstra que aproximadamente metade do território da BHRM é ocupado pelas áreas antrópicas (53,73%) e o restante é coberto por áreas naturais (45,35%) e corpos d?água (0,93%). Onde a maior porcentagem da área antrópica (87%) é utilizada para pastagem, localizada principalmente em locais com declividade de 0 a 5°, e nas regiões com maior inclinação do terreno a cobertura vegetal com maior área proporcionalmente são as florestas, com cerca de 68% ocupando locais com declividade acima de 5°.Geopantanal 2012

    Banco de dados geográfico do meio físico e climático do estado de São Paulo.

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    Um banco de dados geográfico em SIG (Sistema de Informações Geográficas) é constituído de informações que permitem auxiliar na tomada de decisões voltadas para manejo do solo, rotação de culturas, previsões climáticas, levantamentos topográficos, etc. O objetivo do trabalho foi empregar a ferramenta de SIG na montagem do banco de dados de solo, de declividade e climático do Estado de São Paulo. Como dados de entrada foram utilizados o mapa pedológico do IAC (Instituto Agronômico), as informações climáticas de temperatura média, mínima e máxima e de precipitação, fornecidos pelo Agritempo e os dados do sensor SRTM (Shuttle Radar Topography Mission), disponibilizados pela NASA. Como resultado, foram obtidos o mapa pedológico, de declividade e climáticos, nos datuns SAD 69 e Córrego Alegre, na resolução 0,5? X 0,5? de latitude e longitude do Estado de São Paulo

    Canary in the Forest?—Tree mortality and canopy dieback of western redcedar linked to drier and warmer summers

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    Aim: Forest dieback is increasing from unfavourable climate conditions. Western redcedar (WRC)—a culturally, ecologically and economically important species—has recently experienced anomalously high mortality rates and partial canopy dieback. We investigated how WRC tree growth and dieback responded to climate variability and drought using tree-ring methods. Location: Pacific Northwest, USA. Taxon: Western redcedar (Thuja plicata). Methods: We collected tree cores from three tree health status groups (no canopy dieback, partial canopy dieback, and dead trees) at 11 sites in coastal (maritime climate) and interior (continental climate) WRC populations. From growth rates, we computed four growth indices that assessed the resilience to drought and estimated the year of death. Results: Warmer and drier climate conditions in May/June that extended the annual July-to- September dry season reduced radial growth in 9 of 11 sites (1975–2020). WRC trees recovered growth to pre-drought rates within 3 years when post-drought climate conditions were cooler/wetter than average. However, recovery from drought was slower or absent when warmer/drier conditions occurred during the post-drought recovery period, possibly leading to the recent and widespread mortality across the coastal population. WRC mortality was portended by 4–5 years of declining growth. Annually-resolved mortality in coastal populations predominately occurred in 2017–2018 (80% of sampled dead trees), a period that coincided with exceedingly hot temperatures and the longest regionally dry period from May to September (1970–2020). In interior populations, mortality was dispersed among years but associated with warmer and drier conditions from August to September. Main conclusions: Our findings forewarn that a warming climate and more frequent and severe summer droughts, especially in consecutive years, will likely increase the vulnerability of WRC to canopy dieback and mortality and possibly other drought-sensitive trees in one of the world\u27s largest forest carbon sinks

    Ozone depletion events observed in the high latitude surface layer during the TOPSE aircraft program

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    During the Tropospheric Ozone Production about the Spring Equinox (TOPSE) aircraft program, ozone depletion events (ODEs) in the high latitude surface layer were investigated using lidar and in situ instruments. Flight legs of 100 km or longer distance were flown 32 times at 30 m altitude over a variety of regions north of 58° between early February and late May 2000. ODEs were found on each flight over the Arctic Ocean but their occurrence was rare at more southern latitudes. However, large area events with depletion to over 2 km altitude in one case were found as far south as Baffin Bay and Hudson Bay and as late as 22 May. There is good evidence that these more southern events did not form in situ but were the result of export of ozone-depleted air from the surface layer of the Arctic Ocean. Surprisingly, relatively intact transport of ODEs occurred over distances of 900–2000 km and in some cases over rough terrain. Accumulation of constituents in the frozen surface over the dark winter period cannot be a strong prerequisite of ozone depletion since latitudes south of the Arctic Ocean would also experience a long dark period. Some process unique to the Arctic Ocean surface or its coastal regions remains unidentified for the release of ozone-depleting halogens. There was no correspondence between coarse surface features such as solid ice/snow, open leads, or polynyas with the occurrence of or intensity of ozone depletion over the Arctic or subarctic regions. Depletion events also occurred in the absence of long-range transport of relatively fresh “pollution” within the high latitude surface layer, at least in spring 2000. Direct measurements of halogen radicals were not made. However, the flights do provide detailed information on the vertical structure of the surface layer and, during the constant 30 m altitude legs, measurements of a variety of constituents including hydroxyl and peroxy radicals. A summary of the behavior of these constituents is made. The measurements were consistent with a source of formaldehyde from the snow/ice surface. Median NOx in the surface layer was 15 pptv or less, suggesting that surface emissions were substantially converted to reservoir constituents by 30 m altitude and that ozone production rates were small (0.15–1.5 ppbv/d) at this altitude. Peroxyacetylnitrate (PAN) was by far the major constituent of NOy in the surface layer independent of the ozone mixing ratio

    A Measurement of the Ds+ Lifetime

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    A high statistics measurement of the Ds+ lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis of the two decay modes, Ds+ -> phi(1020)pi+ and Ds+ -> \bar{K}*(892)0K+, used for the measurement. The measured lifetime is 507.4 +/- 5.5 (stat.) +/- 5.1 (syst.) fs using 8961 +/- 105 Ds+ -> phi(1020)pi+ and 4680 +/- 90 Ds+ -> \bar{K}*(892)0K+ decays. This is a significant improvement over the present world average.Comment: 5 pages, 3 figures, 2 tables, submitted to PR

    A High Statistics Measurement of the Lambdac+ Lifetime

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    A high statistics measurement of the Lambdac+ lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis technique with particular attention to the determination of the systematic uncertainty. The measured value of 204.6 +/- 3.4 (stat.) +/- 2.5 (syst.) fs from 8034 +/- 122 Lambdac -> pKpi decays represents a significant improvement over the present world average.Comment: Submitted to Physical Review Letter

    Search for CP Violation in the decays D+ -> K_S pi+ and D+ -> K_S K+

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    A high statistics sample of photo-produced charm from the FOCUS(E831) experiment at Fermilab has been used to search for direct CP violation in the decays D+->K_S pi+ and D+ -> K_S K+. We have measured the following asymmetry parameters relative to D+->K-pi+pi+: A_CP(K_S pi+) = (-1.6 +/- 1.5 +/- 0.9)%, A_CP(K_S K+) = (+6.9 +/- 6.0 +/- 1.5)% and A_CP(K_S K+) = (+7.1 +/- 6.1 +/- 1.2)% relative to D+->K_S pi+. The first errors quoted are statistical and the second are systematic. We also measure the relative branching ratios: \Gamma(D+->\bar{K0}pi+)/\Gamma(D+->K-pi+pi+) = (30.60 +/- 0.46 +/- 0.32)%, \Gamma(D+->\bar{K0}K+)/\Gamma(D+->K-pi+pi+) = (6.04 +/- 0.35 +/- 0.30)% and \Gamma(D+->\bar{K0}K+)/\Gamma(D+->\bar{K0}pi+) = (19.96 +/- 1.19 +/- 0.96)%.Comment: 4 pages, 3 figure
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