The land management activities discussed in Section 4.4 are all "human-induced" in the sense that they are carried out by people, usually in intentional efforts to produce food, fiber, and other goods and services that people need or desire. There have been discussions, however, about whether changes in carbon stocks to be reported for credit need to be limited to those that were the direct result of that human activity; those questions are discussed elsewhere in this Special Report (e.g., Section 18.104.22.168).
If it is decided to limit reportable amounts to reduced emissions or increased sinks resulting from "direct human-induced" activities (as the term appears, for example, in Article 3.3), separation of natural from direct and indirect human effects can be approximated in some situations by the application of one or more of the following techniques:
Some of the situations that might be created under potential Article 3.4 activities will provide relatively easy opportunities to separate the direct effects of an activity from those that might be either indirect (i.e., CO2, N, or S fertilization from anthropogenic atmospheric changes) or the result of natural variability in climate conditions. If the narrow definition of activity is chosen, for example, many activities could be applied next to a control plot where the activity was not applied. The carbon stock difference, if any, measured on the two areas would be an indication of the effect of the activity.
In other situations-such as where land-use change is involved (i.e., conversion of cropland to grass)-field operations will be unable to test how the grass would have impacted soil carbon stocks in the absence of indirect effects or natural variation. If a broad definition of activity is chosen, a wholesale change in management (i.e., an improved grazing system over a large area) may be equally difficult to test for indirect effects because retaining an exact model of the prior management system for comparison will be difficult or impossible.
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