Wood products in use are part of a full forest sector carbon balance. Globally, about 3.4 billion m3 of wood is harvested per year, excluding wood burned on-site (FAO, 1997b), and harvest rates are expected to increase at 0.5 percent per year (Solberg et al., 1996). Of the total harvest, about 1.8 billion m3 yr-1 is fuelwood, mainly from the tropics. Most of the harvest in the boreal and temperate zone is industrial roundwood. About one-half to two-thirds of the raw wood finds its way into wood products; the rest is used as energy or is otherwise lost. The annual production of wood materials therefore corresponds to a harvest flux of about 1.6 billion m3, translating to a gross flux into wood products of about 0.3 Gt C yr-1.
The long-term effectiveness of carbon storage in wood products depends on the uses of wood produced through project activities. In projects that stop logging (and perhaps those that stop deforestation, if some of the wood cut during deforestation entered the wood products market), the change in the wood products pool would be negative and would thus offset some of the carbon benefits from the project; this effect would have to be accounted for. In plantation projects, wood that goes into medium- to long-term products (e.g., sawn timber for housing, particle board, paper) represents additional carbon storage. Several (modeling) methods exist for accounting for the storage of long-lived wood products; these methods have been used to calculate the net changes in stocks in several countries (Pingoud et al., 1996; Nabuurs and Sikkema, 1998; Skog and Nicholson, 1998; Winjum et al., 1998; Apps et al., 1999). These methods account for inputs of new products to the pool as well as decay, disposal in landfills, oxidation, and retirement of products from past use, accumulated as far back as individual country's records allow. An IPCC expert group for the land use and forestry sector of the guidelines for GHG inventories completed a report on a description and evaluation of the approaches available for estimating carbon emissions or removals from forest harvesting and wood products (Lim et al., 1998).
If one of the additional activities (see Section 4.4.5) includes carbon in wood products, a method for monitoring changes in the carbon of that compartment will be needed. Monitoring of wood products is possible through national and international statistics on harvesting and trade. The net build-up of carbon in products might be derived from estimates of average lifetimes for different wood products. Keeping track of the wood products stemming from lands under Article 3.3 or 3.4 will be extremely difficult, however. The only practical approach may be to use estimates that are based on data from other forests.
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