Deforestation occurs as a result of fire, disease, wind and other natural means, or as a consequence of human activities related to the harvest of timber for commercial purposes and/or clearing of land for agriculture. Global patterns of deforestation are indicated in Table 7.1. Between 2000 and 2005, the majority of countries in the Caribbean, Europe, North America, Oceania, and Western and Central Asia had no significant changes in forested area, while in Africa nearly all countries lost forestland to agriculture (Kauppi et al. 2006). The countries with the greatest losses in forest averaged a net loss of 8.2 million ha per year, with Brazil (3.1 mil ha yr−1) and Indonesia (1.9 mil ha yr−1) leading the way. The ten countries with the greatest net gains in forest area averaged gains of 5.1 million ha yr−1, with China accounting for the most (4.1 mil ha yr−1). As Table 7.1 shows, forests in temperate and boreal areas have actually expanded. Thus, we conclude that deforestation is mainly a problem of tropical deforestation, but that rates of deforestation appear to be falling.
The UN's Food and Agricultural Organisation (FAO) defines tropical forest ecosystems as having a minimum of 10% crown canopy of trees and/or bamboo; they are generally associated with wild flora, fauna and natural soil conditions and not subject to agricultural practices.