Selecting an integration framework for MRV requires consideration of practical and scientific issues including:

There are two main methods for integration remote sensing and ground-based observations:

All these methods have been used by countries in developing land sector GHG estimates and, when applied correctly, all comply with UNFCCC rules and IPCC guidelines. However, the accuracy of estimates obtained can vary greatly. Tier 3 approaches may be more accurate or precise because they do not have to deploy simplifying assumptions inherent in emission/removal factor based approaches, and because they may be able to accommodate more refined stratification of forest conditions (forest types, ecological and climate conditions, age classes, disturbance and management history, etc.) although the complexity may increase and transparency decrease as a consequence.

Methods of integration are not mutually exclusive. Most countries currently use a combination of integration methods depending on the nature of forest land use, and availability of data. It is sensible to implement a national system progressively within a single integration framework. This makes it possible initially to implement simpler methods to meet short-term needs, without sacrificing the longer-term goals. For example, integration framework can initially represent only a small number of forest strata with the associated small number of growth curves. As more data become available through implementation of improvement plans for identified significant or key categories (Chapter 2, Section 2.2.3) the spatial scope of the integration framework can be expanded. Well-designed frameworks should be able to accommodate increase in estimation complexity and data richness.