Afforestation of former arable land is a current trend in many European countries. In addition to wood, these new forests provide a variety of environmental benefits, such as carbon sequestration and improved water quality. However, there could be negative impacts, such as reduced groundwater recharge. This book provides techniques for estimating the environmental impacts, and guidelines and decision support systems to enable national and international policy makers, and also forest managers, to maximize benefits and minimize the adverse effects of afforestation. The book describes afforestation research and shows the application of a developed decision support system. The book considers three important environmental issues - carbon sequestration in soils and biomass, water surplus and nitrate leaching, reviewing efforts to quantify these effects in the field and model the data into the future. Finally, it shows how detailed models are reduced to "metamodels" suitable for implementation within a real-time management system.