401 research outputs found

    Index de la chronique de jurisprudence. Liste des titres

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    A utiliza√ß√£o de plantas para fitorremedia√ß√£o do solo requer que a concentra√ß√£o do poluente esteja dentro dos limites de toler√Ęncia da planta para que o tratamento seja eficaz. O rebrotamento e crescimento da herb√°cea aqu√°tica Echinochloa polystachya em solo de v√°rzea contaminado por petr√≥leo de Urucu foram estudados por meio do plantio de prop√°gulos em frascos com 2 L de solo contaminado pela mistura de 7 dosagens de petr√≥leo, distribu√≠das entre 0 e 0,46 L m-2. O experimento foi realizado em Casa de Vegeta√ß√£o e as plantas foram monitoradas durante 70 dias. Em resposta ao aumento da dosagem do petr√≥leo, houve diminui√ß√£o da biomassa a√©rea, da propor√ß√£o de biomassa a√©rea viva/a√©rea total, do comprimento da folha e do n√ļmero de folhas. A intera√ß√£o entre dosagem e tempo de exposi√ß√£o levou √† diminui√ß√£o do n√ļmero de folhas, comprimento da folha, altura de inser√ß√£o da primeira folha e aumento do n√ļmero de folhas com comprometimento fitossanit√°rio. A utiliza√ß√£o de E. polystachya para fitorremedia√ß√£o pode estar limitada a solos com baixas dosagens de petr√≥leo de Urucu.The use of plants for the phytoremediation of contaminated soils requires that the concentrations of the pollutant lay within the limits of tolerance of the plant in order to ensure the efficacy of the treatment. The vegetative propagation and growth of the aquatic herbaceous plant Echinochloa polystachya were studied by planting parts of stems in 2 L of v√°rzea soils previously contaminated by crude oil from Urucu, in 7 different dosages of oil ranging from 0 to 0.46 L m-2. The experiment took place in a green house and the plants were monitored during a 70 days period. Increasing the oil concentration lead to the decrease of the above-ground biomass, the ratio alive aerial biomass/total aerial biomass, leaf length and number of leaves. The interaction between dosage and time of exposition contributed for a reduction in the number and length of leaves, height of insertion of the first leaf, and increase of the number of unhealthy leaves. The use of E. polystachya for phytoremediation may be limited to soils with lower concentrations of crude oil from Urucu

    Conhecendo as √°reas √ļmidas amaz√īnicas: uma viagem pelas v√°rzeas e igap√≥s

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    Utilizando uma linguagem simples, este livro sintetiza o conhecimento atual sobre as √°reas √ļmidas amaz√īnicas e sua import√Ęncia para o ciclo hidrol√≥gico e de carbono global. √Č destacada a grande diferen√ßa existente entre as v√°rzeas e os igap√≥s, seus diversos tipos de √°guas e √°reas alag√°veis associadas. A ecologia e fisiologia de plantas como as √°rvores, macr√≥fitas aqu√°ticas e ep√≠fitas s√£o destacados. O potencial de uso dessas plantas tamb√©m foi sintetizado, mostrando como os povos da Amaz√īnia fazem uso das plantas para sua subsist√™ncia. A import√Ęncia dos peixes para a sobreviv√™ncia dos povos ribeirinhos √© discutida, como s√£o tamb√©m apresentados os diferentes tipos de pesca, comercial, de subsist√™ncia, esportiva e de peixes ornamentais. O turismo se utiliza da pesca, e tamb√©m da observa√ß√£o de aves e mam√≠feros aqu√°ticos, estes √ļltimos envoltos em lendas regionais que podem tanto contribuir para a sua preserva√ß√£o, como trazer preju√≠zos √†s popula√ß√Ķes desses importantes animais. Como parte da exuberante biodiversidade das √°reas √ļmidas foi dado destaque ainda aos artr√≥podes, formigas, abelhas, borboletas, aranhas e muitos outros pequenos animais que muitas vezes nos causam nojo, por√©m, esta √© uma vis√£o a ser mudada. Pouqu√≠ssimos artr√≥podes s√£o vetores de doen√ßas, e a grande maioria √© de imensa import√Ęncia para o equil√≠brio do ecossistema, servindo de alimento para diversos animais e reciclando os nutrientes que trazem fertilidade ao ambiente. As amea√ßas √†s √°reas √ļmidas amaz√īnicas s√£o muitas. Entre elas as mais preocupantes s√£o o desmatamento para cria√ß√£o de gado, o plantio de gr√£os como a soja, o estabelecimento de usinas hidrel√©tricas e a explora√ß√£o de g√°s e petr√≥leo, que pode acarretar em acidentes ambientais. A contabiliza√ß√£o de danos ambientais √© necess√°ria e pode ser feita, por√©m, o estabelecimento de atividades de repara√ß√£o dos danos ambientais e a aplica√ß√£o de multas dependem do conhecimento do sistema. Trabalhar em √°reas √ļmidas como pesquisador ou como t√©cnico √© √°rduo, mas profundamente recompensador. Al√©m do contato constante com a fant√°stica fauna, flora e paisagens desses ambientes, os rios, suas cores e mist√©rios s√£o um presente extra. Ainda h√° muito para se estudar nas √°reas √ļmidas amaz√īnicas e este livro busca motivar, especialmente os jovens estudantes a se juntar a n√≥s nessa aventura

    Time of exposure and oil dosage affecting biomass production of the Amazonian semi-aquatic grass Echinochloa polystachya

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    The effects of Urucu crude oil on growth and biomass production of Echinochloa polystachya were studied experimentally. Young plants contaminated with 5 oil doses (0 to 2.64 l.m -2) were monitored at 1, 5, 10, 15 and 20 days after exposure. A significant reduction was observed in leaf humidity and the ratio of live aerial/total biomass related to the increase in oil dosage. Increased exposition time caused a reduction in the number of leaves, aerial biomass, proportion of live aerial/total biomass, total biomass, and an increase of dead aerial biomass. However, root biomass and leaf length were not affected by exposure to oil. The low tolerance of E. polystachya to Urucu crude oil has lead to the mortality of 90% of the plant population in 20 days at the 2.64 l treatment. The death of young individuals of E. polystachya by relatively low dosages of Urucu oil indicates that, in the case of an oil spill in the Amazon varzea, this species would be severely affected, endangering, consequently, the entire environment

    Influence of the flood-pulse on leaf phenology and chlorophyll content in two species of the Igapó forest in Central Amazonia, Brazil

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    In order to verify the influence of flood-pulse dynamics on leaf phenology and concentrations of chlorophyll a, b and total, 15 individuals of two species typical of the black-water igap√≥ forest, Eschweilera tenuifolia and Hevea spruceana, were studied in the lower course of the river Tarum√£-Mirim, Amazonas, Brazil. Leaf phenology was followed weekly from July 1993 to Dezember 1994 and the chlorophyll content was measured in the laboratory every month. Variations in the chlorophyll contents were related to leaf age. Mean concentrations of total chlorophyll in mature and old leaves of E. tenuifolia were 473.5 and 288.6 mg m-2, and 418.5 and 199.0 mg m-2 in H. spruceana. The peak shedding and flush occurred during the aquatic phase.Com o objetivo de verificar a influ√™ncia da din√Ęmica do pulso de inunda√ß√£o na fenologia foliar e conte√ļdo de clorofilas a, b e total, 15 indiv√≠duos adultos de duas esp√©cies t√≠picas das cotas mais baixas da floresta de igap√≥, Eschweilera tenuifolia e Hevea spruceana, foram estudados no baixo curso do rio Tarum√£-Mirim, Amazonas, Brasil. A fenologia foliar foi acompanhada em observa√ß√Ķes semanais de campo de julho de 1993 a dezembro de 1994 e o conte√ļdo de clorofilas foi medido em laborat√≥rio, mensalmente. Mudan√ßas no conte√ļdo de clorofilas relacionaram-se √† idade da folha. As concentra√ß√Ķes m√©dias de clorofila total em folhas maduras e velhas de E. tenuifolia foram de 473,5 e 288,6 mg m-2, e em H. spruceana de 418,5 e 199,0 mg m-2. Na fase aqu√°tica deu-se o pico de abscis√£o e brotamento foliar

    Estrategias reproductivas de la vegetación y sus respuestas al pulso de la inundación en las zonas inundables de la Amazonía Central

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    Los humedales o √°reas que sufren largos per√≠odos de inundaciones peri√≥dicas, asociadas a los grandes r√≠os, cubren aproximadamente el 6% de la Amazonia Brasile√Īa. Precisamente en esta regi√≥n se encuentran localizados los bosques inundados con mayor extensi√≥n y diversidad vegetal del mundo. En esos ambientes, la altura de la columna de agua puede fluctuar durante todo el a√Īo, llegando a valores promedio de hasta 10 m. La previsibilidad y duraci√≥n del pulso de las inundaciones, la abrupta transici√≥n en las condiciones ambientales a lo largo del gradiente topogr√°fico en los m√°rgenes de los r√≠os principales y la intensidad de las corrientes de agua y la din√°mica de los sedimentos representan una fuerte presi√≥n selectiva sobre las poblaciones de plantas y sus sistemas de reproducci√≥n. En este trabajo se examina y discute c√≥mo el ciclo del agua influye en las estrategias de reproducci√≥n sexual y asexual que conducen a la realizaci√≥n del ciclo de vida de las plantas, permitiendo el mantenimiento de sus poblaciones. Tambi√©n se abordan las posibles restricciones sobre los procesos de germinaci√≥n, el establecimiento de pl√°ntulas y la formaci√≥n de bancos de semillas. Adem√°s, se indican algunas lagunas en el conocimiento existente sobre las estrategias reproductivas de la vegetaci√≥n en las planicies de inundaci√≥n de la Amazon√≠a Central y se proponen l√≠neas futuras de investigaci√≥n. Se enfatiza en las especies herb√°ceas, debido a la gran variedad de formas de vida y estrategias reproductivas y su fuerte din√°mica temporal y espacial en respuesta al ciclo hidrol√≥gico. El estudio de la vegetaci√≥n de los ambientes inundados presentados aqu√≠ es relevante, especialmente, debido a los efectos previstos en las poblaciones de estas comunidades ante los escenarios de cambio clim√°tico previstos para la Amazonia.The wetlands associated with great rivers cover about 6% of the Brazilian Amazon, being considered the most extensive and, in terms of flora, the most diverse wetland forest of the world. These environments are subjected to extended periods of flooding, when the height of the water column may fluctuate throughout the year an average of up to 10 m. The predictability, the length of the flood pulse, the abrupt transition in the environmental conditions along the topographic gradient on the banks of major rivers in Central Amazonia and the powerful water and sediment dynamics impose a strong selective pressure on plant populations and on reproductive systems. In this study we examine how the hydrological cycle influences the strategies of sexual and asexual reproduction that lead to the completion of the life cycle and the maintenance of plant populations. Possible constraints to seed germination, seedling establishment and formation of seed banks are also covered, as well as gaps in knowledge of reproductive strategies of the vegetation in floodplains of Central Amazonia. The emphasis is on herbaceous species because of the variety of life forms and reproductive strategies and their strong spatial and temporal dynamics in response to the hydrological cycle. The study of the vegetation of the Amazonian floodplains is even more relevant considering the expected impacts on the populations of these plant communities, if the climate change scenarios predicted for the Amazon become a reality. We conclude by proposing future research directions.Este trabajo contiene partes de los resultados obtenidos de las investigaciones y estudios desarrollados por el grupo de investigaci√≥n de intercambio cient√≠fico proyecto INPA/Max-Planck e Pronex/Fapeam/CNPq financiado por el CNPq de Brasil

    Trait divergence and habitat specialization in tropical floodplain forests trees

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    Habitat heterogeneity of tropical forests is thought to lead to specialization in plants and contribute to the high diversity of tree species in Amazonia. One prediction of habitat specialization is that species specialized for resource-rich habitats will have traits associated with high resource acquisition and fast growth while species specialized for resource-poor habitats will have traits associated with high resource conservation and persistence but slow growth. We tested this idea for seven genera and for twelve families from nutrient-rich white-water floodplain forest (várzea) and nutrient-poor black-water (igapó) floodplain forest. We measured 11 traits that are important for the carbon and nutrient balance of the trees, and compared trait variation between habitat types (white- and black-water forests), and the effect of habitat and genus/family on trait divergence. Functional traits of congeneric species differed between habitat types, where white-water forest species invested in resource acquisition and productive tissues, whereas black-water forest species invested in resource conservation and persistent tissues. Habitat specialization is leading to the differentiation of floodplain tree species of white-water and black-water forests, thus contributing to a high diversity of plant species in floodplain forests

    Life cycle and ecology of Paspalum fasciculatum Willd. ex. Fluegge (Poaceae), in the v√°rzea of the central Amazon

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    Paspalum fasciculatum is a robust perennial C4 grass that occurs in the Central Amazon v√°rzeas. In order to establish the ecology and life cycle of the species in relation to the annual water level fluctuations, twenty plants were randomly selected and monthly observed from September/95 to August/96, in two sites from 23 to 27 m (a.s.l.). The length of stems, and the number of live and dead leaves, sprouts and inflorescence were recorded. The growth of Paspalum fasciculatum is synchronised with the terrestrial phase of the hydrological cycle, reaching during the period of the study a maximum length of 4.53 m. The dormancy and ability of stems to survive subsequent years under flood, and the tolerance of the species to a highly unstable environment allow us to classify it as a extremely adapted "r" strategist, representing the first stages of colonisation on the sedimentary margins of rivers and lakes in the v√°rzea.Paspalum fasciculatum √© uma robusta gram√≠nea C4, perene, de ocorr√™ncia nas v√°rzeas da Amaz√īnia Central. Para estabelecer a ecologia e o ciclo de vida da esp√©cie em rela√ß√£o as flutua√ß√Ķes anuais do n√≠vel do rio, vinte plantas foram marcadas ao acaso e acompanhadas mensalmente, de setembro/95 a agosto /96, em duas √°reas entre 23 e 27 m (s.n.m.). Registrou-se o comprimento do talo, o n√ļmero de folhas verdes e mortas, brotos, e a presen√ßa de infloresc√™ncias. Paspalum fasciculatum sincroniza seu crescimento com a fase terrestre do ciclo hidrol√≥gico, tendo atingido no per√≠odo de estudo o comprimento m√°ximo de 4,53 m. A dorm√™ncia e grande toler√Ęncia dos talos a anos subsequentes de inunda√ß√£o e a capacidade de suportar mudan√ßas bruscas do ambiente f√≠sico, permitem classificar a esp√©cie como estrategista "r", altamente adaptada e representativa dos primeiros est√°gios de coloniza√ß√£o das margens sedimentares de rios e lagos de v√°rzea

    Ecological implications of the reproductive phenology of Salix martiana Leyb. (Salicaceae) in v√°rzea areas of Central Amazonia

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    Salix martiana Leyb. is a plant that occupies margins of Whitewater rivers, at levels higher than 23 m above sea level (a.s.l.). In order to verify the influence of precipitation and annual inundation duration on the phenology of the species, three sites between 23 and 27 m a.s.l. were established. At each site, 25 individuals were labeled and observed weekly during 14 months. In order to establish the medium time for fruit formation, three individuals per site had 25 inflorescences labeled, of which 79% showed fruit formation, with 48 fruits formed per inflorescence. Neither inundation nor precipitation influenced phenology, and the production of seeds was continuous throughout the year. Considering the unstable environment the species inhabits, the pattern of seed production may be an important adaptation to increase reproductive success.Salix martiana Leyb. √© uma planta que ocupa margens de rios de √°gua branca, situando-se em cotas a partir de 23 m sobre o n√≠vel do mar (s.n.m.). Com o objetivo de verificar a influ√™ncia do tempo de inunda√ß√£o anual e da precipita√ß√£o no comportamento fenol√≥gico desta esp√©cie, tr√™s s√≠tios em diferentes cotas, de 23 a 27 m (s.n.m.), foram escolhidos e em cada um deles 25 √°rvores foram marcadas e observadas semanalmente, durante 14 meses. Para determina√ß√£o do tempo m√©dio de forma√ß√£o dos frutos, tr√™s √°rvores por s√≠tio tiveram 25 infloresc√™ncias marcadas, das quais 79% formaram frutos, com uma m√©dia de 48 frutos formados por infloresc√™ncia. N√£o houve interfer√™ncia da inunda√ß√£o ou da precipita√ß√£o em qualquer das fenofases, sendo a produ√ß√£o de sementes cont√≠nua ao longo do ano. Dentro das popula√ß√Ķes n√£o foi observada varia√ß√£o individual nos eventos reprodutivos. Considerando o ambiente inst√°vel habitado pela esp√©cie, a produ√ß√£o ininterrupta de sementes pode representar uma importante adapta√ß√£o para aumentar o sucesso reprodutivo
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