3 resultados para POPULATION DISTRIBUTION

em Repositório Científico da Universidade de Évora - Portugal


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Portugal is characterized by a significant asymmetry in the population distribution/density and economic activity as well as in social and cultural dynamics. This means very diverse landscapes, differences in regional development, sustainability and quality of life, mainly between urban and rural areas. A consequence coherent with the contemporary dynamics: urbanization of many rural areas that loose their productive-agricultural identity and, simultaneously, the reintegration in urban areas of spaces and activities with more rural characteristics. In this process of increasing complexity of organization of the landscape is essential to restore the continuum naturale (between urban and rural areas) allowing closer links to both ways of life. A strategy supported in the landscape, which plays important functions for public interest, in the cultural, social, ecological and environmental fields. At the same time, constitutes an important resource for economic activity, as underlined in the European Landscape Convention. Based on this assumption, and using a multi-method approach, the study aims to analyse a) the links between urban and rural areas in Portugal and b) the reasons why these territories are chosen by individuals as places of work and mobility, residence or evasion, culture and leisure, tranquillity or excitement – meaning overall well-being. Primary information was obtained by a questionnaire survey applied to a convenience sample of the Portuguese population. Secondary data and information will be collected on the official Portuguese Statistics (INE and PORDATA). Understanding the urban-rural links is essential to support policy measures, take advantage from the global changes and challenge many of the existing myths.

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Bonelli’s eagle, Hieraaetus fasciatus , has recently suffered a severe population decline and is currently endangered. Spain supports about 70% of the European population. We used stepwise logistic regression on a set of environmental, spatial and human variables to model Bonelli’s eagle distribution in the 5167 UTM 10 × 10 km quadrats of peninsular Spain. We obtained a model based on 16 variables, which allowed us to identify favourable and unfavourable areas for this species in Spain, as well as intermediate favourability areas. We assessed the stepwise progression of the model by comparing the model’s predictions in each step with those of the final model, and selected a parsimonious explanatory model based on three variables — slope, July temperature and precipitation — comprising 76% of the predictive capacity of the

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Juniperus navicularis Gand. is a dioecious endemic conifer that constitutes the understory of seaside pine forests in Portugal, areas currently threatened by increasing urban expansion. The aim of this study is to assess the conservation status of previously known populations of this species located on its core area of distribution. The study was performed in south-west coast of Portugal. Three populations varying in size and pine density were analyzed. Number of individuals, population density, spatial distribution and individual characteristics of junipers were estimated. Female cone, seed characteristics and seed viability were also evaluated. Results suggest that J. navicularis populations are vulnerable because seminal recruitment is scarce, what may lead to a reduction of genetic variability due solely to vegetative propagation. This vulnerability seems to be strongly determined by climatic constraints toward increasing aridity. Ratio between male and female shrubs did not differ from 1:1 in any population. Deviations from 1:1 between mature and non-mature plants were found in all populations, denoting population ageing. Very low seed viability was observed. A major part of described Juniperus navicularis populations have disappeared through direct habitat loss to urban development, loss of fitness in drier and warmer locations and low seed viability. This study is the first to address J. navicularis conservation, and represents a valuable first step toward this species preservation.