Some of the specific practices within the activities are explicitly included in the Workbook, some could be included with minor modification (see Section 18.104.22.168), and some could be included only with extensive revision. For example, in the cropland management activity, tillage practices are explicitly included, whereas erosion reduction practices are not currently dealt with. The Fact Sheets in Appendix A of Chapter 4 provide a brief assessment of the extent to which the Guidelines can be used to account for the individual activities.
Chapter 4 also identifies the potential carbon net storage of improved management within a land use, land-use change, and off-site carbon storage. Activities with the greatest potential change in the aboveground and below-ground biomass are discussed below.
Cropland management. The following practices are aimed at increasing soil carbon or reducing losses of soil carbon: cropland management on non-flooded soils, conservation tillage, increased crop productivity (i.e., carbon inputs), control of soil water, and erosion reduction. This last activity is a source, so the issues raised above about changes in stocks in 1990 are relevant. The default assumptions in the Guidelines can be adjusted to account for changes in cropland management. For intensive agriculture, these assumptions would be the input factors for carbon inputs. For conservation tillage, the appropriate factors are the tillage assumptions. There are no specific factors to deal with soil erosion or irrigation, except through the use of input factors because these values determine the carbon residues.
Grazing lands management. Increases of stocks of aboveground and below-ground carbon could be accounted for in a manner analogous to that for ARD. Activities that enhance uptake by sinks include those that increase tree numbers; activities that reduce emissions from sources are those that reduce the intensity of grazing. Non-CO2 emissions would be reported under the agriculture sector. Because of the extensive nature of grasslands, the costs of measurement and verification may need to be considered. Changes in fire management would require classification of "management" because experience has shown that the current guidelines are ambiguous. Although the Guidelines do not specify grazing lands, again the input factors could be adjusted to reflect changes in this management practice. Any grazing land under set-aside management would result in uptake of aboveground biomass, which could be accounted for under the "abandonment of managed lands" section in the Guidelines.
Forest management. The build-up of carbon in protected areas could be accounted for if a definition of human-induced activity were to include the act of protection. Agroforestry and forest management (fertilization, thinning, etc.) could be reported in a manner analogous to ARD. The Guidelines can be used for estimating changes in aboveground biomass. As above, changes in carbon stock resulting from changes in forest management could be accounted for under the calculation in the Guidelines for soil carbon and aboveground biomass. Specific data for the assumptions-such as input and tillage factors-would have to be generated, however, as would assumptions for aboveground biomass.
Wood products. If an activity that brings about changes in wood products is included under Article 3.4, the approach in the Guidelines would not be adequate to estimate such changes.
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