In the IPCC, Land Use, Flexible, and Biome definitional scenarios, the harvest/regeneration cycle does not create ARD land. ARD land is created only by changes between forest and non-forest categories.
We assume that the definitions of forest in the IPCC, Land Use, Flexible, and Biome scenarios are such that mature, unharvested stands in both the high- and low-productivity forest are considered forest. For the Land Use scenario, we assume that the observed change in forest cover is associated with an administrative reclassification of land use. Table 3-11 summarizes the human activities that create ARD land for each of the three groups of definitional scenarios.
In the FAO and Land Cover definitional scenarios, ARD land is created through harvest/regeneration cycles, albeit for different reasons. In the FAO scenario, harvest does not create ARD land; subsequent planting of forests in these areas creates ARD land. Under the FAO scenario, naturally regenerated areas do not create ARD land because, for illustrative purposes, we assume that natural regeneration was not considered DHI. In both scenarios, harvested areas that undergo land-use change are considered deforested and create ARD land.
In the Land Cover scenario, harvest causes the stand to cross the threshold of forest cover that is used to define forest. Because any area below the threshold is considered non-forest, harvest is considered deforestation and creates ARD land. Thereafter, it does not matter whether a stand is established through natural regeneration or through planting because the harvested area is already classified as ARD land.
The definition of reforestation in the Land Cover scenario specifies that a planted area becomes ARD land when the stand passes the threshold of forest cover that defines forest (40 percent cover in our example). This definition of reforestation will cause a delay between the planting activity and the creation of ARD land. It ensures that no carbon credit or debit is obtained until the planted area passes the threshold defining a forest.
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