5 resultados para Scale Of Localized Zone

em SAPIENTIA - Universidade do Algarve - Portugal


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Dissertação de Mestrado, Gestão da Água e da Costa, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2010

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Understanding the factors that affect seagrass meadows encompassing their entire range of distribution is challenging yet important for their conservation. We model the environmental niche of Cymodocea nodosa using a combination of environmental variables and landscape metrics to examine factors defining its distribution and find suitable habitats for the species. The most relevant environmental variables defining the distribution of C. nodosa were sea surface temperature (SST) and salinity. We found suitable habitats at SST from 5.8 ºC to 26.4 ºC and salinity ranging from 17.5 to 39.3. Optimal values of mean winter wave height ranged between 1.2 m and 1.5 m, while waves higher than 2.5 m seemed to limit the presence of the species. The influence of nutrients and pH, despite having weight on the models, was not so clear in terms of ranges that confine the distribution of the species. Landscape metrics able to capture variation in the coastline enhanced significantly the accuracy of the models, despite the limitations caused by the scale of the study. By contrasting predictive approaches, we defined the variables affecting the distributional areas that seem unsuitable for C. nodosa as well as those suitable habitats not occupied by the species. These findings are encouraging for its use in future studies on climate-related marine range shifts and meadow restoration projects of these fragile ecosystems.

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Tese de dout., Ciências do Mar, da Terra e do Ambiente (Ciências do Mar-Oceanografia Física), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011

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Serpa and Moura region, in the South of Portugal, have important agricultural potential as well as important agricultural resources that can and should be used and developed, in spite of economic and social depression signs reinforced by demographic difficulties that can lead to desertification in some areas. The main farms' Technical-Economic Orientation (TEO) is olives production, to produce olive oil, since this region has excellent conditions for the activity development. Some mobilizations traditionally made in olive groves lead to soil erosion and make the farm vehicles mobility much more difficult, namely those used in cultural operations. The maintenance of a soil cover in the olive grove space between lines is good, both because it favours the vehicles mobility, it promotes the rain water infiltration and, last but not the least, the soil airing. The objective of this work has been to make a socio-economic characterization of a zone of Serpa and Moura Councils in which a project of soil covers under olive trees is being developed. At the same time cultural accounts were made for the different situations under the study - irrigated olive grove with spontaneous vegetation in the space between lines, irrigated olive grove with seeded vegetation in the space between lines, irrigated olive grove with herbicide application in the space between lines, dry olive grove with spontaneous vegetation in the space between lines, dry olive grove with seeded vegetation in the space between lines and dry olive grove with herbicide application in the space between lines. The survey shows farmers in this area are younger then usual, although they don't have a high level of formal education, general or specific in agriculture. Farm areas are usually high, which can be determinant for the proposed technology adoption. Installation and operation costs for the olive grove are higher on the irrigated olive grove, but of course expected productions are also higher. For this production technology profits coming from olives production are higher then the operation costs. However, in the dry olive grove technology costs are always higher then the profits, being profitability only due to subsidies. The importance of soil cover maintenance, in this region, beside the benefits in what concerns erosion, infiltration and soil airing, is also due to its capacity to minimize the risk farmer's face.

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Tese de doutoramento, Ciências do Mar, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015