Definition: The Food and Agriculture Organization (FAO) conducts periodic questionnaire surveys through the Global Forest Resources Assessment (FRA) in which forest is defined as “Land spanning more than 0.5 hectare with trees higher than 5 meters and a canopy cover of more than 10%, or trees able to reach these thresholds in situ.” The definition excludes agricultural production (e.g. fruit orchards) and urban parks, but includes commercial plantations (e.g. rubber or cork). The last FRA was conducted in 2010 and is the source of the forest cover change map opposite.
Trends: In 2010 an estimated 31% of total land area was forested and, of this, 36% was primary forest, 57% naturally regenerated forest, and 7% planted forest. Although the rate of deforestation has declined, it remains high, with an annual estimated loss of around 13 million hectares of forest per year (1 hectare = 10,000 m2). The predominant cause of deforestation is the conversion of tropical forest to agricultural land. New forest planting and natural expansion of existing forests does, however, reduce net forest loss to an estimated 5.8 million hectares per year.
Significance for infections: Forests are habitats for animal reservoirs and vectors of a wide range of infectious diseases that may infect humans either opportunistically or as part of the pathogen’s natural lifecycle. Forest associated infections where humans are the definitive host are rare, but notably include malaria transmitted by forest-associated anopheles
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