Since the first United Nations Conference on Human Environment in Stockholm (1972), forests in general and tropical forests in particular, have been receiving increased attention from the world community. A high point in international interest was reached at the United Nations Conference on Environment and Development (UNCED) at Rio de Janeiro (1992), which devoted a full chapter, entitled "Combating Deforestation", of its Agenda 21 to the issues of forest conservation and development and adopted the "non-legally binding, authoritative statement of principles for a global consensus on the management, conservation and sustainable development of all types of forests".
The valuation of the functions of forests has changed at a very quick pace. The introductory paragraph of the World Forest Inventory in 1963 read as follows: "In the present decade, with world attention focussed on development, there is a need for concerted efforts to provide a complete picture of the resources available for a steadily growing population. A worldwide effort to step up the utilization level of the rich tropical forest resources seems imperative to avoid a world with the vast majority of its population living in conditions of increasing wood shortage. The 1963 World Forest Inventory takes its place as part of this endeavour".
Today environmental functions of forests are high on the agenda. There is even a holistic perception of world forests as part of the "global ecosystem". Models are being built to study global forests as a source or a sink of carbon in the atmosphere, depending on whether there is an increase or decrease in global forest biomass. Several questions have been posed by policy-makers, the scientific community and the public at large. What is the area and mass of the remaining world forests? At what rate and in what way are they changing? What are the causes of change? What are the ecological, economic and social impacts? And so on.
It is against this background of global concern that the present publication should be considered. Efforts have been made to reflect some of the important global concerns, related to forest resources issues of the early twenty-first century. However, much remains to be achieved in this respect.