Reforestation is defined in 16/CMP.1, Annex, paragraph 1(c) as follows:
Reforestation is the direct human-induced conversion of non-forested land to forested land through planting, seeding and/or the human-induced promotion of natural seed sources, on land that was forested but that has been converted to non-forested land. For the first commitment period, reforestation activities will be limited to reforestation occurring on those lands that did not contain forest on 31 December 1989 (16/CMP.1, Annex, paragraph 1(c)).
Therefore, reforestation is the conversion of land that was not forested on 31 December 1989 to forested land. It is distinct from afforestation, which is the conversion of land that has not contained a forest for at least 50 years to forested land.