This book presents and analyses some of the most challenging aspects in maintaining forest health. Deforestation is a very important issue in the evolution of the environment. Forests are disappearing and the causes are well-documented. The authors are recognised experts in their fields and they present the results of studies developed in Africa, Latin America and Asia. The effects of using household fuelwood consumption, including those of resettlements and refugees, as well as the need for direct investments in the forest sector are studied. Some studies on the trends and drivers of deforestation, plant coverage, forest regeneration and tree trunk diameter estimations were developed using quantitative methods. In the various chapters of the book, the authors present studies wherein the effect of the actions of man on both deforestation and in reforestation politics is considered. It is divided into two sections; the first one deals with the analysis of causes and the effects of deforestation; the second section is mainly related to a large variety of quantitative studies of deforestation. The contents of the contributions of this section are concerned with quantifying different deforestation issues. Each chapter elaborates using concrete studies, insights, models and methods; they provide results for real problems. It is remarkable that they also provide methodologies which can be used in similar research.