Afforestation is the direct human-induced conversion of land that has not been forested for a period of at least 50 years to forested land through planting, seeding and/or the human-induced promotion of natural seed sources.
UNFCCC, as quoted in Global Canopy Programme, "Glossary of Terms" - "The Little REDD Book. A Guide to governmental and non-governmental proposals for reducing emissions from deforestation and degradation." (Global Canopy Foundation, November 2008.) UNFCCC. Glossary of CDM Terms. EB41. 2008.
Establishment of forest through planting and/or deliberate seeding on land that, until then, was under a different land use, implies a transformation of land use form non-forest to forest.
Terms and Definitions - FRA 2020, FAO, 2018 (http://www.fao.org/3/I8661EN/i8661en.pdf).