In other words, it compares the amount of yearly, or other time period, harvested wood, or any other forest product, with the annual increment from the forest. If annual increment is not know, allowable cut can be used as a surrogate. If the ratio is smaller or equal to one, it means that the country is harvesting less, or equal, to the annual forest increment. This represents the sustained yield principle. If the ratio is more than one, a country is over-harvesting its wood, or other specific forest resource.
Forests serve multiple ecological, socioeconomic, and cultural roles in many countries.
They are among the most diverse and widespread ecosystems of the world. They support employment and traditional uses, and biodiversity. There is general concern over human impact on forest health, and the natural processes of forest growth and regeneration. Combating deforestation to preserve soils, water, air and biological diversity is explicitly considered in Agenda 21. This indicator is relevant for assessing the sustainability of forest management when interpreted over a long time period.