Of the forest that remains, less than one-fourth could be considered relatively undisturbed by human activity. Forests are currently expanding in much of the industrialised world, while shrinking in most of the developing world. By contrast, the industrialised countries gained 9 million hectares of forested land. A new measure of forest resource availability helps illustrate the increasing scarcity of forests in many countries. By 2025, the number of people living in forest-scarce countries could triple to 4.6 billion.
Population dynamics are among the primary underlying causes of forest decline.
Poverty, corruption, inequitable access to land and wasteful consumption practices also influence the decisions of governments, corporations, and individuals to cut and clear forests. The interactions of these forces are most evident in areas such as South Asia, Central America and Sub-Saharan Africa, where poverty, rapid population growth, and weak institutions contribute to forest losses and severe environmental degradation. The dominant force in forest loss is growth in the demand for farmland. Subsistence agriculture is the principal cause of forest loss in Africa, Asia and much of Latin America. Total wood consumption has tripled during the 20th century.