Index de la chronique de jurisprudence. Liste des titres

A utilização de plantas para fitorremediação do solo requer que a concentração do poluente esteja dentro dos limites de tolerância da planta para que o tratamento seja eficaz. O rebrotamento e crescimento da herbácea aquática Echinochloa polystachya em solo de várzea contaminado por petróleo de Urucu foram estudados por meio do plantio de propágulos em frascos com 2 L de solo contaminado pela mistura de 7 dosagens de petróleo, distribuídas entre 0 e 0,46 L m-2. O experimento foi realizado em Casa de Vegetação e as plantas foram monitoradas durante 70 dias. Em resposta ao aumento da dosagem do petróleo, houve diminuição da biomassa aérea, da proporção de biomassa aérea viva/aérea total, do comprimento da folha e do número de folhas. A interação entre dosagem e tempo de exposição levou à diminuição do número de folhas, comprimento da folha, altura de inserção da primeira folha e aumento do número de folhas com comprometimento fitossanitário. A utilização de E. polystachya para fitorremediação pode estar limitada a solos com baixas dosagens de petróleo 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 várzea 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

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

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

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 igapó forest, Eschweilera tenuifolia and Hevea spruceana, were studied in the lower course of the river Tarumã-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 influência da dinâmica do pulso de inundação na fenologia foliar e conteúdo de clorofilas a, b e total, 15 indivíduos adultos de duas espécies típicas das cotas mais baixas da floresta de igapó, Eschweilera tenuifolia e Hevea spruceana, foram estudados no baixo curso do rio Tarumã-Mirim, Amazonas, Brasil. A fenologia foliar foi acompanhada em observações semanais de campo de julho de 1993 a dezembro de 1994 e o conteúdo de clorofilas foi medido em laboratório, mensalmente. Mudanças no conteúdo de clorofilas relacionaram-se à idade da folha. As concentrações médias 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 aquática deu-se o pico de abscisão e brotamento foliar

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

Los humedales o áreas que sufren largos períodos de inundaciones periódicas, asociadas a los grandes ríos, cubren aproximadamente el 6% de la Amazonia Brasileña. Precisamente en esta región se encuentran localizados los bosques inundados con mayor extensión y diversidad vegetal del mundo. En esos ambientes, la altura de la columna de agua puede fluctuar durante todo el año, llegando a valores promedio de hasta 10 m. La previsibilidad y duración del pulso de las inundaciones, la abrupta transición en las condiciones ambientales a lo largo del gradiente topográfico en los márgenes de los ríos principales y la intensidad de las corrientes de agua y la dinámica de los sedimentos representan una fuerte presión selectiva sobre las poblaciones de plantas y sus sistemas de reproducción. En este trabajo se examina y discute cómo el ciclo del agua influye en las estrategias de reproducción sexual y asexual que conducen a la realización del ciclo de vida de las plantas, permitiendo el mantenimiento de sus poblaciones. También se abordan las posibles restricciones sobre los procesos de germinación, el establecimiento de plántulas y la formación de bancos de semillas. Además, se indican algunas lagunas en el conocimiento existente sobre las estrategias reproductivas de la vegetación en las planicies de inundación de la Amazonía Central y se proponen líneas futuras de investigación. Se enfatiza en las especies herbáceas, debido a la gran variedad de formas de vida y estrategias reproductivas y su fuerte dinámica temporal y espacial en respuesta al ciclo hidrológico. El estudio de la vegetación de los ambientes inundados presentados aquí es relevante, especialmente, debido a los efectos previstos en las poblaciones de estas comunidades ante los escenarios de cambio climático 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 investigación de intercambio científico proyecto INPA/Max-Planck e Pronex/Fapeam/CNPq financiado por el CNPq de Brasil

Trait divergence and habitat specialization in tropical floodplain forests trees

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

Germinação da semente e desenvolvimento pós-seminal de Victoria amazonica (Poepp.) J. C. Sowerby (Nymphaeaceae) na Amazônia Central

The Amazon floodplains are specific ecosystems with high biodiversity and endemism, divided in varzeas, white fertile waters, and Igapos with poor and acid waters, black or clear, and mixed waters between the two typologies. The main purpose of this investigation was to characterize the seed germination and post-seminal development of Victoria amazonica (Poepp.) J.C. Sowerby, one of the few hydrophytes occurring in varzea and mixed waters in the region. In addition, it was evaluated the influence of environmental characteristics on the growth of the plants. Germination was monitored in seeds with and without scarification, in control and treatments with water low oxygen and in the dark. The plant development was monitored in field and laboratory; material from juvenile and adult plants was collected at six sampling sites near Manaus. Germination is favored in the dark, in hypoxic conditions, in water and seed coat shaved. The seedling has two cotyledons, one inside the seed and the other with an acicular shape, eophyll deltoid-hastate, abortive primary root and adventitious roots. New eophylls and the first metaphyll appear in twenty-day-old plants. The stem is rhizomatous. The mixed water environment was not very different from the varzea which is reflected in a similar chemical composition of the plants of both systems. The rhizomes of the varzea environment have caloric value three times higher than that of mixed water. This condition and the presence of larger leaves suggest the varzea floodplain to be more favorable environment for growth of Victoria amazonica.As várzeas amazônicas são ecossistemas específicos de alta biodiversidade e endemismo, que consistem em várzeas, com águas transparentes e férteis em nutrientes, e Igapós com água pobre e ácida, escura ou clara, e águas mistas entre os dois tipos referidos. O principal objetivo dessa investigação foi caracterizar a germinação das sementes e o desenvolvimento pós-seminal de Victoria amazonica (Poepp.) J.C. Sowerby, que é considerada uma das poucas hidrófitas de várzea e águas mistas da região. Além disso, foi avaliada a influência das características ambientais no crescimento das plantas. A germinação foi monitorada em sementes com e sem escarificação, no controle e tratamentos com água de baixo teor de oxigênio e no escuro. O desenvolvimento da planta foi acompanhado no campo e laboratório; material de plantas juvenis e adultas foi coletado em seis amostras de locais próximos de Manaus. A germinação é favorecida no escuro, em condições hipóxicas, água e semente escarificada. A plântula tem dois cotilédones, um que permanece no interior da semente e outro acicular, eofilo deltoide-hastado, raiz primária abortiva e raízes adventícias. Novos eofilos e primeiro metafilo formam-se em plantas de vinte dias. O caule é rizomatoso. Ambiente de água mista não foi diferente da várzea, comprovado pela composição química similar das plantas de ambos sistemas. Os rizomas da várzea têm valores calóricos três vezes maior do que o de água mista. Esta condição e a presença de folhas maiores sugerem que a várzea é ambiente mais favorável para crescimento de Victoria amazonica

Growth of Pouteria glomerata (Sapotaceae), a tree species from the Central Amazonian floodplain, under long-term flooding

To understand the occurrence of P. glomerata in the Amazonian várzea we investigated the morpho-physiological responses to long-term flooding. Seedlings of P. glomerata were subjected to two flooding treatments (partial and total) for six months. Following flooding treatments, we examined light-saturated photosynthesis (A), the potential quantum yield of photosystem II (inferred as the Fv/Fm ratio), height, number of leaves (NF), stem diameter at the base of the plant (DCC), leaf area and plant biomass. We found a decrease in gas exchange parameters and growth rates, whereas leaf damage increased with flooding. After six months of flooding, leaf area, and the total plant biomass as well as the biomass of the vegetative organs (leaf, stem and root) were lower in flooded seedlings than in control, non-flooded plants. As flooding level increased assimilated carbon was mainly allocated to stems. However, flooding treatments had no significant effect on specific leaf area, the root/shoot ratio and dry mass of roots. Totally submerged roots of flooded seedlings were strongly affected, showing to be the most critical condition for maintenance of physiological metabolism. P. glomerata was affected by long-term flooding. Thus, P. glomerata exhibited adjusts morpho-fisiological which makes it possible for this species to occur in the Amazon floodplain forest.Para entender a ocorrência de P. glomerata na várzea amazônica, investigamos as respostas morfo-fisiológicas a longo período de inundação. Durante seis meses, plântulas de P. glomerata foram submetidas a dois tratamentos de inundação (parcial e total) para análise da assimilação fotossintética líquida (A), eficiência quântica do fotosistema II (referido como Fv/Fm), altura, número de folhas, diâmetro do colo do caule (DCC), área foliar e biomassa da planta. Encontramos um decréscimo da atividade de trocas gasosas, das taxas de crescimento e danos foliares com o aumento do nível de inundação. Após seis meses de experimento, a área foliar, a biomassa dos órgãos vegetativos (raiz, caule e folha) e a biomassa total das plântulas inundadas foram menores que das plântulas controle, plântulas não-inundadas. De acordo com o aumento do nível de inundação, a biomassa fotoassimilada foi alocada principalmente para o caule. Somente área foliar específica, razão raiz / parte aérea e massa seca de raiz não apresentaram diferenças entre os tratamentos. As plântulas totalmente inundadas foram fortemente comprometidas, demonstrando ser esta à condição mais crítica para a manutenção do metabolismo fisiológico. P. glomerata foi afetada pelo longo período de inundação, no entanto a espécie revela adaptações morfo-fisiologica que justifica a sua ocorrência em florestas de várzea