Monitoring forest carbon in a Tanzanian woodland using interferometric SAR: a novel methodology for REDD+
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Date
2015
Journal Title
Journal ISSN
Volume Title
Publisher
Springer
Abstract
Background: REDD+ implementation requires establishment of a system for measuring, reporting and verification
(MRV) of forest carbon changes. A challenge for MRV is the lack of satellite based methods that can track not only
deforestation, but also degradation and forest growth, as well as a lack of historical data that can serve as a basis
for a reference emission level. Working in a miombo woodland in Tanzania, we here aim at demonstrating a novel
3D satellite approach based on interferometric processing of radar imagery (InSAR).
Results: Forest carbon changes are derived from changes in the forest canopy height obtained from InSAR, i.e.
decreases represent carbon loss from logging and increases represent carbon sequestration through forest growth.
We fitted a model of above-ground biomass (AGB) against InSAR height, and used this to convert height changes
to biomass and carbon changes. The relationship between AGB and InSAR height was weak, as the individual plots
were widely scattered around the model fit. However, we consider the approach to be unique and feasible for
large-scale MRV efforts in REDD+ because the low accuracy was attributable partly to small plots and other
limitations in the data set, and partly to a random pixel-to-pixel variation in trunk forms. Further processing of the
InSAR data provides data on the categories of forest change.
The combination of InSAR data from the Shuttle RADAR Topography Mission (SRTM) and the TanDEM-X satellite
mission provided both historic baseline of change for the period 2000–2011, as well as annual change 2011–2012.
Conclusions: A 3D data set from InSAR is a promising tool for MRV in REDD+. The temporal changes seen by
InSAR data corresponded well with, but largely supplemented, the changes derived from Landsat data.
Description
© 2015 Solberg et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License
(http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly credited.
Keywords
Forest monitoring, Biomass, Carbon, InSAR