Afforestation of former arable land is currently a common change in land use in many European countries. In addition to wood production, the new forests will provide a variety of environmental services, such as carbon sequestration or improved water quality. At the same time there may be negative impacts, such as reduced groundwater recharge. The contents of the book aims at developed techniques to estimate the environmental impacts, and guidelines and decision support systems (DSS) to enable national and international policy makers, but also forest managers, to maximize the benefits and minimize the adverse effects of afforestation. This book will describe afforestation research and shows the application of the developed decision support system. The results should be applicable throughout northwest Europe and could be extended elsewhere. This book considers three of the most important environmental issues - carbon sequestration in soils and biomass, water surplus and nitrate leaching. The book describes the research to quantify these effects in the field and model them into the future. It will explain how the more detailed models were reduced to "metamodels" suitable for implementation within a real-time management system.