Browsing by Author "Viana, H."
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- Assessment of forest biomass for use as energy. GIS-based analysis of geographical availability and locations of wood-fired power plants in PortugalPublication . Viana, H.; Cohen, Warren B.; Lopes, D.; Aranha, J.Following the European Union strategy concerning renewable energy (RE), Portugal established in their national policy programmes that the production of electrical energy from RE should reach 45% of the total supply by 2010. Since Portugal has large forest biomass resources, a significant part of this energy will be obtained from this source. In addition to the two existing electric power plants, with 22 MW of power capacity, 13 new power plants having a total of 86.4 MW capacity are in construction. Together these could generate a combination of electrical and thermal energy, known as combined heat and power (CHP) production. As these power plants will significantly increase the exploitation of forests resources, this article evaluates the potential quantities of available forest biomass residue for that purpose. In addition to examining the feasibility of producing both types of energy, we also examine the potential for producing only electric energy. Results show that if only electricity is generated some regions will need to have alternative fuel sources to fulfil the demand. However, if cogeneration is implemented the wood fuel resource will be sufficient to fulfill the required capacity demand.
- Compostagem de resíduos de curtumes com resíduos florestaisPublication . Pereira, J.; Viana, H.; Marques, F.; Teixeira, D.; Perdigão, A.; Pinto, A.; Rodrigues, P.O presente estudo teve como objectivo avaliar a viabilidade da obtenção de resíduos compostados a partir de resíduos produzidos pela indústria de curtumes e de resíduos provenientes da indústria de transformação florestal, com vista à sua aplicação em povoamentos florestais. Para o efeito foram recolhidos dois tipos resíduos vulgarmente produzidos numa empresa de curtumes, nomeadamente raspa da tripa e aparas em bruto. As aparas em bruto foram sujeitas a um pré-tratamento através da lavagem com água. A raspa da tripa e as aparas em bruto com e sem pré-tratamento foram misturadas com resíduos florestais (serrim e casca de pinheiro bravo) e sujeitas a compostagem durante 135 dias. Os materiais utilizados na compostagem e os resíduos compostados obtidos foram analisados em termos físicos, químicos e microbiológicos, de acordo com o exposto no Decreto-Lei n.º 118/2006. Concluímos que os resíduos compostados com raspa da tripa e aparas em bruto, com e sem pré-tratamento, apresentaram teores de metais pesados bastante inferiores aos valores limite estipulados por Lei. Observou-se ainda que o pré- tratamento das aparas em bruto conduziu à redução da presença de sais em cerca de 50% nos resíduos compostados obtidos. Os resultados obtidos permitiram comprovar que estes resíduos compostados podem ser aplicados aos solos. Este facto é um factor importante para as indústrias de curtumes que podem desta forma dar uma utilização aos resíduos gerados pela sua actividade.
- Estudo e Diagnóstico de Necessidades de Formação Profissional Florestal na Região Dão-LafõesPublication . Amaral, N.; Bica, A.; Ferreira, A.; Mendes, A.; Viana, H.; Pato, L.; Fachada, M.; Serra, N.Este estudo tem assim por objectivo tornar mais competitivo o sector florestal da RDL, através da melhoria da formação profissional dos seguintes intervenientes nesta área de actividade: produtores florestais, viveiristas, empreiteiros florestais, madeireiros e técnicos florestais. Simultaneamente, este trabalho poderá servir de guião a futuras acções de formação para o sector florestal, originando assim uma maior racionalidade na aprovação das mesmas. Permite ainda avaliar a formação realizada até ao momento, e contribuir para a percepção dos aspectos a serem melhorados nas futuras acções de formação, incidindo sobretudo nos aspectos práticos da sua actividade, isto é, no “saber fazer”.
- A simplified methodology for the correction of Leaf Area Index (LAI) measurements obtained by ceptometer with reference to Pinus Portuguese forestsPublication . Lopes, D.; Nunes, L; Walford, N; Aranha, J.; Sette, CJ; Viana, H.; Hernandez, CForest leaf area index (LAI) is an important structural parameter controlling many biological and physiological processes associated with vegetation. A wide array of methods for its estimation has been proposed, including those based on the sunfleck ceptometer, a ground-based easy-to-use device taking non-deForest leaf area index (LAI) is an important structural parameter controlling many biological and physiological processes associated with vegetation. A wide array of methods for its estimation has been proposed, including those based on the sunfleck ceptometer, a ground-based easy-to-use device taking non-deForest leaf area index (LAI) is an important structural parameter controlling many biological and physiological processes associated with vegetation. A wide array of methods for its estimation has been proposed, including those based on the sunfleck ceptometer, a ground-based easy-to-use device taking non-destructive LAI measures. However, use of ceptometer in pine stands leads to the underestimation of LAI due to foliage clumping of this species. Previous studies have proposed a correction of biased LAI estimates based on the multiplication by a constant factor. In this study, a new method for obtaining a correction factor is proposed by considering the bias (the difference between the ceptometer measure and the reference LAI) as a function of the stand structural variables, namely the basal area. LAI data were collected from 102 sampling plots (age range: 14-74) established in Pinus pinaster forests all across northern Portugal. Data from 82 sampling plots were used for the adjustment of the LAI ceptometer correction model, while the remaining 20 plots were used for the model validation. The observed LAI ranged from 0.34 to 6.4 as expected from the large heterogeneity of the sampled pine stands. Significant differences were detected between LAI values estimated by ceptometers and LAI reference values. Different correction methods have been compared for their accuracy in predicting LAI reference values. Based on the results of the statistical analysis carried out, the new proposed LAI correction outperformed all the other methods proposed so far. The new approach for bias reduction proposed here has the advantage of being easily applied since the basal area is almost always available from forest inventory or can be inferred from remote sensing surveys. However, the bias correction model obtained is site-specific, being dependent on stand species composition, soil fertility, site aspect, etc. and should therefore be applied only in the study area. Nonetheless, the development of a correction methodology based on an allometric approach has proved to greatly improve LAI ceptometer estimations.