Replanting of forests on lands that have previously (or more recently) contained forests, but that have been converted to some other use (e.g. agricultural production) (see Deforestation). According to some definitions the difference between afforestation and reforestation is the period of time that the land has been without forest. As a result reforestation is establishing forests on land that has more recently contained forests, while afforestation is establishing forests on land that has been without forests for a very long time. Article 3.3 of the Kyoto Protocol refering to accounting of LULUFC activities makes no difference between the two however. (see also Afforestation and LULUCF)

Sources: (general source)