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Resultados de la búsqueda

Mostrando ítems 1 a 9 de 27.
  1. Library Resource
    Artículos de revistas y libros
    Diciembre, 2010
    Francia, Global

    Global environmental changes observed during recent decades are likely to have had an impact on the distribution of species. Currently, silver fir (Abies alba) is becoming established in the subalpine forests of the west central Alps at elevations higher than 2000 ma.s.l.; prior to the 1970s its upper altitudinal limit was 2000 m. Several hypotheses could explain this recent expansion of the upper tree-limit. Silver fir regeneration could be linked (1) to land-use changes or (2) to current climatic warming.

  2. Library Resource
    Artículos de revistas y libros
    Diciembre, 2010
    Francia

    Once the conditions that led to the creation of the Société Civile des Terres du Larzac (SCTL) have been introduced, the companion modelling approach used with this group of farmers is presented. The agent-based model co-constructed with a group of researchers and technicians is then described, as well as the way it was used to confront scenarios developed by the SCTL to envision management options of the forest massif, with scenarios developed by the farmers to improve the current functioning of their farms

  3. Library Resource
    Artículos de revistas y libros
    Diciembre, 2010
    Francia, Global

    Global environmental changes observed during recent decades are likely to have had an impact on the distribution of species. Currently, silver fir (Abies alba) is becoming established in the subalpine forests of the west central Alps at elevations higher than 2000 ma.s.l.; prior to the 1970s its upper altitudinal limit was 2000 m. Several hypotheses could explain this recent expansion of the upper tree-limit. Silver fir regeneration could be linked (1) to land-use changes or (2) to current climatic warming.

  4. Library Resource
    Artículos de revistas y libros
    Diciembre, 2010
    Argelia, Francia, Nigeria, Mauritania, Malí, Burkina Faso, Senegal, Etiopía, Níger, Eritrea, Sudán, Camerún, República Centroafricana, Sudán del Sur, Chad, Europa, África, América central, América del Sur

    We propose a flexible and adaptable framework to assist the quick design of models dealing with the durability of the extensive livestock systems at the territorial scale. This metamodel results from the collaborative design starting from MAS developed on 7 sites in Latin America, France and Senegal. It is composed of four packages: Agent, Community, Space and Vegetation-Herd. We illustrate these packages with examples extracted from the various models. The role of this tool is discussed in order to show its advantages and its limits

  5. Library Resource
    Artículos de revistas y libros
    Diciembre, 2010
    Argelia, Francia, Nigeria, Mauritania, Malí, Burkina Faso, Senegal, Etiopía, Níger, Eritrea, Sudán, Camerún, República Centroafricana, Sudán del Sur, Chad, Europa, África, América central, América del Sur

    We propose a flexible and adaptable framework to assist the quick design of models dealing with the durability of the extensive livestock systems at the territorial scale. This metamodel results from the collaborative design starting from MAS developed on 7 sites in Latin America, France and Senegal. It is composed of four packages: Agent, Community, Space and Vegetation-Herd. We illustrate these packages with examples extracted from the various models. The role of this tool is discussed in order to show its advantages and its limits

  6. Library Resource
    Artículos de revistas y libros
    Diciembre, 2010
    Alemania

    Several TerraSAR-X satellite images acquired in high resolution spotlight mode with different polarisations for two study sites in southern Germany were used to distinguish forest from other land cover classes (agriculture, built-up, water bodies) using logistic regression models. In general, we observed that the mean and particularly the standard deviation of the backscatter were viable measures to discriminate land cover classes. Both measures were lowest for water bodies and highest for built-up areas, with agricultural areas and forest in intermediate positions.

  7. Library Resource
    Documentos de conferencias e informes
    Diciembre, 2010
    Francia

    Using a sample of French crop farms during the 1999-2006 period, we test whether lesstechnically efficient farmers are more likely to engage in organic farming in order to benefitfrom conversion subsidies. Despite some limitations in our data, we find no evidence of suchselection effect. On the contrary, our estimation results indicate that more technically efficientfarmers are more likely to convert to organic farming. This finding is found to be robust to themethod of calculation of efficiency scores, either parametric or non-parametric.

  8. Library Resource
    Artículos de revistas y libros
    Diciembre, 2010
    Francia

    Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentation) in cultivated areas of the European loess belt. This study aimed to determine the impact of rainfall seasonality and land use change on soil erosion over the last 40 years in a 94-ha cultivated catchment of Normandy (France). To this end, scenarios representative of the different land use conditions were simulated using the STREAM expert-based erosion model. A 13 years long sequence of rainfall events was run with this model.

  9. Library Resource
    Artículos de revistas y libros
    Diciembre, 2010
    Francia, Europa

    The Coteaux de Gascogne region, an upland area in south-western France, is a site where studies related to the future of landscapes and the sustainability of natural resource management are well documented. The local agricultural system is induced by a “house centred” society with the particularity of passing on the inheritance and farm estate identically from one generation to the next. This system generates a mosaic landscape made up of field crops, grasslands and woodlots.

  10. Library Resource
    Artículos de revistas y libros
    Diciembre, 2010
    Francia, Europa

    The Coteaux de Gascogne region, an upland area in south-western France, is a site where studies related to the future of landscapes and the sustainability of natural resource management are well documented. The local agricultural system is induced by a “house centred” society with the particularity of passing on the inheritance and farm estate identically from one generation to the next. This system generates a mosaic landscape made up of field crops, grasslands and woodlots.

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