Browsing by Author "Dias, A.C."
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- Biomass allometry and carbon factors for a Mediterranean pine (Pinus pinea L.) in PortugalPublication . Correia, A.A.; Tomé, Margarida; Pacheco, C.A.; Faias, Sónia; Dias, A.C.; Freire, J.; Carvalho, P.O.; Pereira, J.S.Forests play an important role in the global carbon balance because they offset a large portion of the carbon dioxide emitted through human activities. Accurate estimates are necessary for national reporting of greenhouse gas inventories, carbon credit trading and forest carbon management but in Portugal reliable and accessible forest carbon measurement methodologies are still lacking for some species. The objective of this study was to provide forest managers with a comprehensive database of carbon factors and equations that allows estimating stand-level carbon stocks in Pinus pinea L. (P. pinea), regardless of the tree inventory information available. We produced aboveground biomass and stem volume equations, biomass expansion factors (BEF) by component as well as wood basic density (WBD) and component carbon fraction in biomass. A root-to-shoot ratio is also presented using data from trees in which the root system was completely excavated. We harvested 53 trees in centre and south Portugal covering different sizes (6.5 to 56.3 cm), ages (10 to 45 years) and stand densities (20 to 580 trees ha–1). The results indicate that aboveground allometry in P. pinea is not comparable with other pines and varies considerably with stand characteristics, highlighting the need to develop stand-dependent factors and equations for local or regional carbon calculations. BEFaboveground decreases from open (1.33 ± 0.03 Mg m–3) to closed stands (1.07 ± 0.01 Mg m–3) due to a change in biomass allocation pattern from stem to branches. Average WBD was 0.50 ± 0.01 Mg m–3 but varies with tree dimensions and the root-to-shoot ratio found was 0.30 ± 0.03. The carbon fraction was statistically different from the commonly used 0.5 factor for some biomass components. The equations and factors produced allow evaluating carbon stocks in P. pinea stands in Portugal, contributing to a more accurate estimation of carbon sequestered by this forest type.
- Estudo comparativo do sistema radicular dos porta-enxertos SO4, 99R e 1103P em Antrossolos de GranitoPublication . Pacheco, C.M.A.; Dias, A.C.; Pedroso, V.; Gouveia, J.P.; Gomes, C.; Martins, S.; Rodrigues, P.; Lopes, C.M.Aproveitando a oportunidade do arranque de um ensaio de comparação de três porta-enxertos (SO4, 99R e 1103P) na casta Touriga Nacional procedeu-se ao estudo do sistema radicular de seis videiras por porta-enxerto. Avaliou-se a distribuição espacial das raízes pelo método do perfil vertical e quantificou-se a biomassa das raízes, do bacelo e do tronco. Os resultados evidenciam os seguintes aspectos: - A máxima concentração de raízes está localizada entre os 20 e os 50cm de profundidade, decrescendo depois acentuadamente com a profundidade até atingir a rocha granítica; - São raras as raízes que atingem a rocha compacta, mas observou-se a existência de raízes muito finas na zona de contacto lítico; - A distribuição radicular é muito irregular de um plano para outro de observação, não obedecendo a nenhum padrão em particular, mas fortemente dependente da compacidade e da localização espacial das unidades morfológicas resultantes do tipo de preparação do solo à plantação; - Não foram identificadas diferenças ou tendências consistentes entre os porta-enxertos testados, nem quanto à biomassa radicular nem em relação à distribuição de raízes em profundidade, nem mesmo quanto ao número de raízes por m2 (densidade); - A meia encosta, com deficiente drenagem na zona de contacto lítico, apresenta para todos os porta-enxertos menor densidade e biomassa radicular quando comparada com as posições de topo e da base da encosta; - A análise das imagens dos cepos revela uma forte assimetria quanto à distribuição espacial das raízes intra e inter porta-enxertos imputáveis à selecção, preparação e técnica de plantação do Bacelo, bem como à técnica de preparação do solo
- The revolving door : evidence from the United Kingdom, Germany, France, Spain, Belgium, Greece and BrazilPublication . Dias, A.C.; Santos, A.R. dos; Sousa, A.; Crisóstomo, D.; Pinto, G.; Pereira, L.; Alexandre, M.; Capaz, R.; Paulo, T; Ramiro, P.The following study analyses the academic background and careers of 175 members of Governments and Central Banks of seven countries (Belgium, Brazil, France, Germany, Greece, Spain and United Kingdom) for the years 1975 and 2015, in order to verify whether the “Revolving Door Theory” can be applied to these cases. After some research on the curricula vitae of the members of Governments and Central Banks, we found that, for instance, that more Government and Central Bank members studied abroad for the case of the UK and US than for the other countries. We also found that it is more common for Central Bank executive members to obtain PhDs than it is the case for Government members. Moreover, external promotions in the Central Banks in 1975 were quite relevant but no cases were registered for 2015; for Governments, the trend was the exact opposite, no external promotions in 1975 but many cases in 2015. While it is not possible to find irrefutable evidence to sustain the Revolving Door hypothesis, it is still possible to find recurrent patterns in different countries that may be explained by that theory. More expanded databases and a larger selection of countries is required for that analysis.