Reforestation refers to "the establishment of trees on land that has been cleared of forest within the relatively recent past." Operational forestry definitions of reforestation often include the establishment of trees on land that has just been harvested. With such a definition, areas subject to conventional forest harvesting and regeneration cycles would come within the domain of Article 3.3 of the Protocol at their first post-1990 harvest and regeneration cycle. This definition could have major implications for the size of the land base included as lands under Article 3.3 (see Chapter 3).
In some definitions, reforestation is the conversion of land use back to forest after a period of some other land use. The IPCC Guidelines, which were developed explicitly for carbon inventory, used such a definition of reforestation: "the planting of forests on lands which have, historically, previously contained forests but which have been converted to some other use."
Most of the definitions for reforestation collected by Lund (1999) arise from this forestry perspective and appear to include regeneration after harvesting. Some are very explicit: "Reforestation areas are temporarily unstocked areas caused by harvesting, wind breaks, natural disasters and so on. These areas have to be reforested artificially (usually within 3 years, under certain circumstances within maximal 8 years) or with methods of natural regeneration (usually within 8 years, under certain circumstances within maximal 11 years). In Austria, reforestation has always been recognized as a part of forest management and has never been linked to land-use change."
Such definitions of reforestation do not involve transition from a non-forest to forest state (unless, for example, a strict canopy-cover definition of forest is used). Instead, these definitions are activity-based; they do not reflect a change of land-use designation. This factor raises several options for combinations of definitions based on land use, land cover, and activities that are considered in the definitional scenarios of Chapter 3.
One must consider the different types of reestablishment methods. Decision 9/CP.4 includes the phrase "direct human-induced activities of afforestation, reforestation, and deforestation." Some definitions of reforestation restrict the activity to the planting of trees (e.g., the IPCC definition) or the "artificial establishment" of trees (see Chapter 3), which could be taken to exclude methods based on more natural regeneration. Most forest regeneration is carried out through "natural" reestablishment from seed remaining on the site or from retained seed-trees. Sometimes the seed-bed is prepared by mechanical or chemical treatment. Only a small percentage of forest area is reestablished by direct planting. If the definition is broadly encompassing with regard to regeneration methods, other questions still arise. For example, should land-use practices that lead to an increase in woody cover (e.g., invasion by woody weeds) be counted as reforestation? Chapter 3 deals with some aspects of this issue; Chapter 4 (Section 4.4.3) takes up other aspects.
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