688 resultados para lakeshore wetlands


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In the process of riverine forest restoration, increasing emphasis has been given to the study of herbaceous and shrub species. However, for many of these we still lack basic knowledge, such as reproduction biology. Therefore, the objective of this study was to characterize the production, seed germination and reproductive capacity of Tibouchina clavata (Pers.) Wurdack., a species of wide distribution in wetlands. Fruits were collected from different mother trees located on the southern coast of São Paulo state and, after processing, were subjected to germination under constant temperatures of 25 and 30°C, and alternated temperatures of 25-30°C in the first essay, and at 15, 20, 25, 30, 35, 40°C in another essay, and at 25 °C with presence or absence of light. 10 plants were marked and, in each one, the number of fruits per plant and seed number per fruit were determined to characterize their reproductive capacity. The species germinates over a wide temperature range (15 to 35 °C), and the optimum temperature was in the range of 20 to 30 °C. Seed didn't germinate at 40 °C and could be characterized as being of absolute positive photoblastism. In general, there were over 1600 seeds per fruit and 85.000 seeds per plant. The high seed yield, coupled with good germination percentage demonstrated that this is a species with high reproductive potential.

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Sponge spicules are siliceous microfossils that are especially useful for analysis of sandy fluvio-lacustrine sediments. Sponge spicules in a long sediment core (~550 cm below surface), consisting of fine sand, sandy silt, and organic-rich mud, recovered from the floodplain of the Nabileque River, southern Pantanal, Brazil (S20°16′38. 3″/W57°33′00. 0″), form the basis of a novel paleoenvironmental interpretation for this region. Optically stimulated luminescence dates constrain the timing of deposition to the middle-late Holocene and all spicules identified are typical of the Brazilian cerrado biome. The base of the section is dominated by Oncosclera navicella Carter 1881, Metaniaspinata Carter 1881, and Corvospongilla seckti Bonetto and Ezcurra de Drago 1966, which indicate a lotic to semi-lotic environment strongly influenced by an actively meandering river channel at ~6. 7-5. 7 ka BP. The appearance of Heterorotula fistula Volkmer-Ribeiro and Motta 1995, Dosilia pydanieli Volkmer-Ribeiro 1992 and Radiospongilla amazonensis Volkmer-Ribeiro and Maciel 1983 at ~340 cm downcore suggests a reduction in flowing water and a more stable lentic environment, consistent with deposition in an oxbow lake. This oxbow lake environment existed during an interval of regional aridity between ~4. 5 and 3. 9 ka BP. Spicules, as well as phytoliths and diatoms, are highly variable moving up-section, with species from both lotic and lentic ecosystems present. Above ~193 cm, the total abundance of spicules declines, consistent with wetter climate conditions and development of an underfit river similar to the modern floodplain. Results support hypotheses related to migration of the Paraguay River inferred from geomorphological studies and add a key southern-region dataset to the emerging Holocene database of paleoenvironmental records from the Pantanal wetlands. © 2012 Springer Science+Business Media Dordrecht.

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The invasive behavior of melaleuca (Melaleuca quinquenervia) plants in wetlands is due to its aggressive regeneration strategy, which is based on its seeds germination performance. Understanding of the eco-physiological aspects of the seed germination in melaleuca plants may significantly contribute for the development of management strategies. The objective of this research was to learn how the germination of M. quinquenervia seeds are affected by light and temperature. Melaleuca seeds were placed on filter paper moistened with 12 ml of distilled water at temperatures between 10 and 45°C. Germination was evaluated in dark and light conditions. Seed germination, first count of seed germination (seven days), germination speed index and germination mean time were determined up to 40 days after seeding, when germination had ceased in most of the treatments. After that period, the seeds were transferred to conditions of 30°C and light, which was found to be ideal in the previous phase. Seed germination was daily evaluated up to 63 days when it was again observed no longer to occur. The treatment repetitions were distributed in the growth-chamber according to a completely randomized design in a factorial scheme (eight temperatures x two light conditions) and four repetitions. The data were submitted to analysis of variance with the F test and the means were adjusted to polynomial and non linear regression models. The highest seed germination performance was observed to take place under conditions of 27.3°C with light. The temperatures of 35 and 40°C in the dark induced thermal inhibition of seed germination. The temperature of 45°C was lethal to the seeds.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Caribbean policymakers are faced with special challenges from climate change and these are related to the uncertainties inherent in future climate projections and the complex linkages among climate change, physical and biological systems and socioeconomic sectors. The impacts of climate change threaten development in the Caribbean and may well erode previous gains in development as evidenced by the increased incidence of climate migrants internationally. This brief which is based on a recent study conducted by the Economic Commission for Latin America and the Caribbean (LC/CAR/L.395)1 provides a synthesis of the assessment of the economic and social impacts of climate change on the coastal and marine sector in the Caribbean which were undertaken. It provides Caribbean policymakers with cutting-edge information on the region’s vulnerability and encourages the development of adaptation strategies informed by both local experience and expert knowledge. It proceeds from an acknowledgement that the unique combination of natural resources, ecosystems, economic activities, and human population settlements of the Caribbean will not be immune to the impacts of climate change, and local communities, countries and the subregion as a whole need to plan for, and adapt to, these effects. Climate and extreme weather hazards related to the coastal and marine sector encompass the distinct but related factors of sea level rise, increasing coastal water temperatures, tropical storms and hurricanes. Potential vulnerabilities for coastal zones include increased shoreline erosion leading to alteration of the coastline, loss of coastal wetlands, and changes in the abundance and diversity of fish and other marine populations. The study examines four key themes in the analysis: climate, vulnerability, economic and social costs associated with climate change impacts, and adaptive measures.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Climate change is a continuous process that began centuries ago. Today the pace of change has increased with greater rapidity because of global warming induced by anthropogenically generated greenhouse gases (GHG). Failure to effectively deal with the adverse outcomes can easily disrupt plans for sustainable economic development. Because of the failure of export agriculture over the last several decades, to provide the economic stimuli needed to promote economic growth and development, Jamaica, like many other island states in the Caribbean subregion, has come to rely on tourism as an instrument of transformation of the macro-economy. It is believed this shift in economic imperative would eventually provide the economic impetus needed to generate much needed growth and development. This assessment has shown that tourism is not only a leading earner of foreign exchange in Jamaica and a major creator of both direct and indirect jobs but, also, one of the principal contributors to the country‟s Gross Domestic Product (GDP). The rapid expansion of the industry which occurred over the last several decades coupled with disregard for sound environmental practices has led to the destruction of coral reefs and the silting of wetlands. Because most of the industry is located along the coastal region it is extremely vulnerable to the adverse effects of climate change. Failure to address the predictable environmental challenges of climate change, with some degree of immediacy, will not only undermine, but quickly and seriously impair the capacity of industry to stimulate and contribute to the process of economic development. To this end, it important that further development of industry be characterised by sound economic and social planning and proper environmental practices.

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Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)