The definitions of forest can vary greatly, and different classes will be needed to support the major categories. Tree cover alone is not enough to distinguish between forests and plantations. The international definition proposed by the 2010 FAO Forestry Resource Assessment: "land spanning more than 0.5 ha with trees higher than 5 metres and canopy cover of more than 10 percent, or trees able to reach these thresholds in situ . It does not include land that is predominantly under agricultural or urban land use." - FAO. 2010. Global forest resources assessment 2010, Main report, FAO Forestry Paper 163. Rome.