Doutoramento em Engenharia Florestal e dos Recursos Naturais / Instituto Superior de Agronomia. Universidade de LisboaAgroforestry integrates woody vegetation with crop and/or animal production. This combination can benefit from ecological and economic interactions that allow better use of natural resources and improved economic performance. But despite financial support offered through policy, the implementation of new agroforestry systems has not been widespread in the European Union. This thesis aimed to develop additional scientific knowledge on the potential of agroforestry systems in terms of productivity and environmental benefits. The method consisted in improving a bio-physical process-based model (Yield-SAFE) and an integrated bio-economic model (Farm-SAFE) and using both to model four different agroforestry systems in different edaphoclimatic conditions in Europe. Four different agroforestry tree-densities were compared to no-tree and tree-only monoculture alternatives. The results showed that: 1) in terms of productivity, the inclusion of trees in agricultural land increases the overall accumulated energy but the accumulated energy per tree decreases as the tree density of trees increases; 2) agroforestry options present a greater capacity of reducing soil erosion, nitrate leaching and increases the carbon sequestration; 3) agroforestry systems can act as more sustainable methods of food production and 4) options without trees are more interesting financially but these option are also the most polluting. And even though the consideration of a monetary valuation of the environmental services offered, agroforestry options would just become more interesting if there is a change on how public financial help is allocated to the sector. The findings of this work reflect what has been previously seen in scientific literature, particularly in terms of the capacity of agroforestry systems to be more productive than monoculture systems, whilst at the same time providing environmental benefits. However, relatively low profitability means that they still fail to attract farmers, the main agents of agroforestry uptake and currently, arable and forestry tend to receive higher subsidies making these land uses more attractive to farmers but considering environmental benefits would make agroforestry a more interesting optionN/
