Planting of new forests on lands that historically have not contained forests.
(UNFCCC glossary, 8 March 2007)
The establishment of a forest, stand or tree crop on an area not previously forested, or on land from which forest cover has very long been absent.
(EEA glossary, 13 August 2007)
Afforestation and reforestation both refer to establishment of trees on non-treed land. Reforestation refers to establishment of forest on land that had recent tree cover, whereas afforestation refers to land that has been without forest for much longer. A variety of definitions differentiate between these two processes. Some definitions of afforestation are based on phrases such as "has not supported forest in historical time;" others refer to a specific period of years and some make reference to other processes, such as "under current climate conditions."
The IPCC Guidelines define afforestation as the "planting of new forests on lands which, historically, have not contained forests."
Some definitions emphasize a change in land-cover or land-use designation-for example, "The establishment of a forest or stand in an area where the preceding vegetation or land use was not forest" (Helms, 1998)-although this definition could equally fit many definitions of reforestation.
If afforestation and reforestation are defined in similar terms-distinguished only by the period of time that the land was without forest-then the actual time cut-off between them does not matter. Article 3.3 deals with afforestation and reforestation activities in exactly the same way. Other issues, however, affect the application of these terms. These issues relate to the sequence of human activities prior to, and the actual mode of establishment of, new trees. The important point, however, is that if both actions are treated equivalently in terms of accounting, their precise distinction is not important for the implementation of the Protocol.
(http://www.grida.no/climate/ipcc/land_use/047.htm)
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