Food and Agriculture Organization of the United Nations (FAO)
Definitions & Technical notes:
Forest includes natural forests and forest plantations. It is used to refer to land with a tree canopy cover of more than 10 per cent and area of more than 0.5 ha. Forests are determined both by the presence of trees and the absence of other predominant land uses. The trees should be able to reach a minimum height of 5 m. Young stands that have not yet but are expected to reach a crown density of 10 percent and tree height of 5 m are included under forest, as are temporarily unstocked areas. The term includes forests used for purposes of production, protection, multiple-use or conservation (i.e. forest in national parks, nature reserves and other protected areas), as well as forests stands on agricultral lands (e.g. windbreaks and shelterbelts of trees with a width of more than 20 m), and rubberwood plantations and cork oak stands. The term specifically excludes stands of trees established primarily for agricultural production, for example fruit tree plantations. It also excludes trees planted in agroforestry systems.
Although there is an agreed and clear definition of forest, not all countries apply this definition. In many northern countries, areas with a crown cover of less than 20% are not considered as real forest land. 'Temporarily unstocked areas' refer to areas that have been designated as forest area, but not yet planted, or more often, areas where storm or fire has removed a large part of the forest cover. Unless aggressively restocked with trees, such areas can take a long time to re-establish forests naturally.