Options for monitoring and estimating historical carbon emissions from forest degradation in the context of REDD+

Abstract

Measuring forest degradation and related forest carbon stock changes is more challenging than measuring deforestation since degradation implies changes in the structure of the forest and does not entail a change in land use, making it less easily detectable through remote sensing. Although we anticipate the use of the IPCC guidance under the United Framework Convention on Climate Change (UNFCCC), there is no one single method for monitoring forest degradation for the case of REDD+ policy. In this review paper we highlight that the choice depends upon a number of factors including the type of degradation, available historical data, capacities and resources, and the potentials and limitations of various measurement and monitoring approaches. Current degradation rates can be measured through field data (i.e. multi-date national forest inventories and permanent sample plot data, commercial forestry data sets, proxy data from domestic markets) and/or remote sensing data (i.e. direct mapping of canopy and forest structural changes or indirect mapping through modelling approaches), with the combination of techniques providing the best options. Developing countries frequently lack consistent historical field data for assessing past forest degradation, and so must rely more on remote sensing approaches mixed with current field assessments of carbon stock changes. Historical degradation estimates will have larger uncertainties as it will be difficult to determine their accuracy. However improving monitoring capacities for systematic forest degradation estimates today will help reduce uncertainties even for historical estimates.

Choose satellites to monitor deforestation

“…First, governments and the IPCC need to accept that satellites are the only efficient and realistic way to provide monitoring for REDD+ 5,6 . This must be enshrined in international law through the UNFCCC process and documented in detail.…”

Using Annual Landsat Time Series for the Detection of Dry Forest Degradation Processes in South-Central Angola

“…However, one general method to measure carbon across the landscape does not yet exist and the aspect of forest degradation in this context has long been disregarded [26,27]. Remote sensing in combination with ground data has been identified as being one of the key methods to map and monitor forest dynamics [28], partially because historical trends (including deforestation, afforestation, forest degradation, and regeneration) can only be identified with space-based remote sensing time series due to the poor ground data availability in many developing countries [29].…”

Comment on Gebhardt et al. MAD-MEX: Automatic Wall-to-Wall Land Cover Monitoring for the Mexican REDD-MRV Program Using All Landsat Data. Remote Sens. 2014, 6, 3923–3943

“…Although we acknowledge the considerable difficulty of degradation detection using available remote sensing historical datasets, this key limitation was not discussed by Gebhardt et al [1]. Indeed, detecting degradation is one of the most pressing problems as regards building the necessary baselines and MRV systems for REDD+ [14,15]. In our opinion, it is not possible to accurately detect forest degradation in systems that make use only of relatively coarse optical data (Landsat) and which rely on digital processing only.…”