The implementation of policies to reduce emissions from deforestation and forest degradation (REDD) in developing countries requires cost-effectively obtained accurate and precise estimates of abated emissions at the national scale. Data accuracy and precision is relevant to secure investor confidence, especially if they are connected to international carbon markets. National-level monitoring is often preferred to that at project-level in order to reduce the risk of leakage or displacement of emissions. Cost-effectiveness is relevant for the suppliers of REDD credits (derived from abated emissions from deforestation and degradation) to maximise their gains.

As described in the 2008 GOFC-GOLD sourcebook for REDD¹...

For REDD schemes, monitoring the areal extent of deforestation and forest degradation requires that all forestland within a country (or project reference region) is assessed using consistent methodologies at repeated intervals, and that the results are verified with ground-based or fine-resolution observations (DeFries et al. 2007). However, definitions used currently for ‘deforestation’ and ‘degradation’ vary widely among countries and experts. While the United Nations Framework Convention on Climate Change (UNFCCC) and its Kyoto Protocol give definitions for forestlands and deforestation (Table 1), there is no unique definition so far for forest degradation. But, in addition to allowing for huge variations...

Estimating aboveground forest biomass is the most critical step in quantifying carbon stocks and fluxes from tropical forests (Gibbs et al. 2007). This is because the carbon stored in the aboveground living biomass of trees is typically the largest pool and the most directly impacted by deforestation and degradation. However, it is also critical to consider soil carbon stock estimation for some regions, such as Southeast Asia’s peat-swamp forests, where soils are a massive source of carbon emissions following deforestation (Hooijer et al. 2006; Page et al. 2002).

No methodology can yet directly measure forest carbon stocks across a landscape...

Combining measurements of changes in forest area with estimates of carbon stock densities enables estimation of emissions from deforestation or forest degradation over large regions, and with the updated version of the IPCC GPG-LULUCF, methods are available for estimating carbon emissions from deforestation at national and project scales (DeFries et al. 2007).

There are two fundamentally different, but equally valid, approaches to estimating carbon stock changes (Brown and Braatz 2008, see Figure 2): the stock-difference approach, and the gain-loss approach.

Stock-difference approach. This method estimates the difference in carbon stocks in a particular pool¹⁰ at two moments in time. It...

Monitoring is a central element in an international REDD scheme, not only to detect and credit future emission reductions, but also to establish credible baselines founded on historical trends. Today, multiple options exist to monitor deforestation, degradation and changes in forest carbon stocks. To increase cost-effectiveness, sampling and stratification techniques have been developed for both remote sensing and ground-based monitoring of deforestation, degradation and carbon stock assessments.

Remote sensing technology is especially appropriate for large-scale monitoring, particularly deforestation. Satellite-based estimates of forest carbon stocks are likely to become more accessible over the next decades as new technologies emerge and technical...