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A tree-based approach for modelling interception loss from evergreen oak medite...
Pereira, F.L.; Gasch, J.H.C.; David, J.S.; David, T.S.; Monteiro, P.R.; Valente, F.Evaporation of rainfall intercepted by tree canopies is usually an important part of the overall water balance of forested catchments and there have been many studies dedicated to measuring and modelling rainfall interception loss. These studies have mainly been conducted in dense forests; there have been few studies on the very sparse forests which are common in dry and semi-arid areas. Water resources are sca...
Modelling interception loss from evergreen oak Mediterranean savannas: applicat...
Pereira, F.L.; Gash, J.H.C.; David, J.S.; David, T.S.; Monteiro, P.R.; Valente, F.In a previous study, it was shown that an isolated, fully saturated tree-crown behaves like a wet bulb, allowing evaporation of intercepted rainfall to be estimated by a simple diffusion equation for water vapour. This observation was taken as the basis for a new approach in modelling interception loss fromsavanna-type woodland, whereby the ecosystem evaporation is derived by scaling up the evaporation from ind...
Aerodynamic conductances in a sparse mixed oak woodland (Quercus rotundifolia L...
Pereira, F.L.; Valente, F.; Gazarini, L.C.; David, J.S.The study of heat and mass exchange between the vegetation and its local environment plays a central role in the analysis of plant-atmosphere interactions. These studies can be undertaken at different scales, ranging from individual leaves to isolated trees or even the canopy scale. In each of these cases, heat and mass fluxes depend on the use of adequate values of transfer conductances. Within a broader study...
Radiation balance of an isolated holm oak tree (Quercus rotundifolia Lam.) in a...
Pereira, F.L.; Valente, F.; David, J.S.In closed canopy forests the energy absorbed by the trees can be adequately estimated solely from the vertical radiation fluxes. However, in isolated or widely spaced trees this approach is no longer valid and radiation fluxes in all directions must be accounted for. An adequate estimate of the tree available energy is critical to model and calculate both interception losses and transpiration. Within a study wh...
Greenhouse watching system using multi-technologies
Metrôlho, J.C.; Cruz, S.; Morato, J.; Pereira, F.L.; Lopes, E.Traditional agriculture uses empiric methods and is very exposed to meteorological conditions. To increase the agriculture production, greenhouses had appeared to allow crops with higher quality. Greenhouses also permit the study of cause-effect concepts that by them allow building models that improve the crop’s production and quality. Based on this reality, this paper presents a system developed by researchers...
Multi-monitorização de estufa agrícola
Morato, J.; Cruz, S.; Pereira, F.L.; Metrôlho, J.C.A agricultura tem recorrido, tradicionalmente, a métodos empíricos que não rentabilizavam a produção e estava fortemente dependente das condições meteorológicas. Para melhorar a produção agrícola, surgiram as estufas agrícolas que permitem culturas de elevado valor acrescentado. Estas permitem também a elaboração de estudos de conceitos de causa-efeito, que possibilitam a construção de modelos e sistemas para m...
Transpiração em povoamentos adultos de eucalipto e de pinheiro bravo
Pereira, F.L.; David, J.S.; Madeira, M.V.Foi realizado um estudo com o objectivo de quantificar os consumos de água por transpirarão em dois povoamentos adultos de eucalipto (Eucalyptus globulus Labbill) e de pinheiro bravo (Pinus pinaster Aiton), respectivamente. A estimativa destes consumos foi feita recorrendo a dois métodos distintos: o balanço de água no solo e o modelo de Penman-Monteith (aplicado numa versão unilaminar). Os resultados obtidos i...
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