Land Use, Land-Use Change and Forestry

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3.3.2.5. Carbon Pools that Could be Considered and How They are Impacted by ARD Activities

Section 2.2.5.3 discusses various carbon pools that could be included in carbon accounting for the purposes of the Kyoto Protocol. This section discusses carbon pools from the specific perspective of ARD activities. These carbon pools are affected as follows (see Table 3-6):

• Living biomass. Aboveground (stems, branches, leaves, flowers, and fruits) and below-ground (roots) living biomass will sequester carbon at a rate and to a total magnitude that depends on species, climate, and site quality. Even if forests are allowed to continue to grow, carbon stock in living biomass will eventually reach a maximum. It takes at least decades and more commonly centuries for forests to reach their maximum carbon storage potential. That carbon storage potential also depends on the level of forest management and natural disturbances. The living biomass carbon in areas where new forest is created will increase. If below-ground living biomass is not included in the accounting of deforestation, emissions to the atmosphere would be underreported. In afforestation or reforestation, sequestration rates would be underreported.
• Litter and debris. Following creation of new forest, carbon in litter and woody debris (dead organic matter) increases over time. In deforestation, large amounts of debris are usually generated at the time of tree-felling. Amounts remaining on the ground may be low if logging debris is burned or removed from the site but can be substantial if debris is simply retained on site or if trees are not felled but simply killed by chemical injection. Amounts of litter and woody debris are usually higher in natural forest from which little or no timber has previously been harvested than in plantations (Ruhiyat, 1995).
• Soil. On previously cultivated land where new forest is created, soil organic matter is expected to increase for decades to centuries (O'Connell and Sankaran, 1997). Soil organic matter will decrease rapidly following deforestation if land is subsequently cultivated. Changes in soil organic matter are likely to be small if the soil is not cultivated.
• Wood products/landfills. Some ecosystem carbon removed during harvest or deforestation may be stored in forest products and landfills rather than immediately returning to the atmosphere.
  If the harvest/regeneration cycle does not create ARD land, the proportion of the world wood supply derived from ARD land will be very small. In the FAO scenario, on the other hand, wood product stocks from ARD land could be quite significant, depending on whether the harvest that precedes reforestation is reported as a stock change. If wood products are included in carbon stock assessments, the initial loss of carbon following harvest on the stand level would be lower. The rate of increase in carbon stocks on ARD land also would not diminish as fast. The long-term effect would not be very different, however, from excluding wood products because only a portion of harvested wood usually is stored in long-lived timber products and because share also decays with time (Marland and Schlamadinger, 1999).
  Whether any wood derived from ARD land results in a net increase in forest product and landfill carbon pools depends on future global harvest levels and the fate of the harvested material. In any case, it will be very difficult to track the fate of timber harvested from ARD land and distinguish it from all other harvested material. If (improved) wood product management is a separate activity under Article 3.4, wood products created under ARD lands would have to be excluded from Article 3.3 to avoid double-counting. If all wood products from a particular ARD land were to be assigned to that land and counted under Article 3.3, this accounting approach would be the "production approach" (IPCC, 1999). As a consequence, these wood products would have to be excluded from the account of an importer of these products to avoid double-counting. If the importer were to count the carbon stock change from imported wood products, this would be the "stock change approach" (IPCC, 1999). The "atmospheric flow approach" in IPCC (1999) is not compatible with Article 3.3 because it does not provide a change in carbon stocks but gross flows of carbon to or from the atmosphere.

Table 3-6: Changes in components of terrestrial carbon stocks under different land-use changes. Note that, initially, carbon in litter and woody debris may increase following deforestation. Aboveground biomass and litter can also decrease (e.g., because of harvest or natural disturbances).

a It is assumed here that upon conversion of forest to grazing land, woody debris is not, or is only partly, removed. Dead roots, in particular, would not normally be removed. If woody debris is removed or burned, only dead roots would add to the short-term increase of woody litter. b If forest is subsequently harvested and used for wood production.