SAR tomography for the retrieval of forest biomass and height: Cross-validation at two tropical forest sites in French Guiana

REMOTE SENSING OF ENVIRONMENT

卷:175

Article

Dinh Ho Tong Minh^1,2  Thuy Le Toan²  Rocca, Fabio³  Tebaldini, Stefano³  Villard, Ludovic²  Rejou-Mechain, Maxime^4,5  Phillips, Oliver L.⁶  Feldpausch, Ted R.⁷  Dubois-Fernandez, Pascale⁷  Scipal, Klaus⁸  Chave, Jerome⁴ 

[1] Inst Natl Rech Sci & Technol Environm & Agr, IRSTEA, UMR TETIS, Montpellier, France

[2] Univ Toulouse 3, UMR CNRS 5126, Ctr Etud Spatiales BIOsphere CESBIO, F-31062 Toulouse, France

[3] Politecn Milan, Dipartimento Elettron Informaz & Bioingn, I-20133 Milan, Italy

[4] Univ Toulouse 3, UMR CNRS 5174, Lab Evolut & Diversite Biol, F-31062 Toulouse, France

[5] UMIFRE 21 USR 3330 CNRS MAEE, French Inst Pondicherry, Pondicherry, India

[6] Univ Leeds, Sch Geog, Univ Rd, Leeds LS2 9JT, W Yorkshire, England

[7] Univ Exeter, Coll Life & Environm Sci, Geog, Exeter EX4 4QJ, Devon, England

[8] Off Natl Etud & Rech Aerosp, Toulouse, France

关键词: Aboveground biomass;    BIOMASS mission;    French Guiana;    Paracou;    Nouragues;    TropiSAR;    P-band SAR tomography;    Tomography phase;    Vertical forest structure;   

DOI  :  10.1016/j.rse.2015.12.037

来源: Elsevier

【 摘 要 】

Developing and improving methods to monitor forest carbon in space and time is a timely challenge, especially for tropical forests. The next European Space Agency Earth Explorer Core Mission BIOMASS will collect synthetic aperture radar (SAR) data globally from employing a multiple baseline orbit during the initial phase of its lifetime. These data will be used for tomographic SAR (TomoSAR) processing, with a vertical resolution of about 20 m, a resolution sufficient to decompose the backscatter signal into two to three layers for most closed-canopy tropical forests. A recent study, conducted in the Paracou site, French Guiana, has already shown that TomoSAR significantly improves the retrieval of forest aboveground biomass (AGB) in a high biomass forest, with an error of only 10% at 1.5-ha resolution. However, the degree to which this TomoSAR approach can be transferred from one site to another has not been assessed. We test this approach at the Nouragues site in central French Guiana (ca 100 km away from Paracou), and develop a method to retrieve the top-of-canopy height from TomoSAR. We found a high correlation between the backscatter signal and AGB in the upper canopy layer (i.e. 20-40 m), while lower layers only showed poor correlations. The relationship between AGB and TomoSAR data was found to be highly similar for forests at Nouragues and Paracou. Cross validation using training plots from Nouragues and validation plots from Paracou, and vice versa, gave an error of 16-18% of AGB using 1-ha plots. Finally, using a high-resolution LiDAR canopy model as a reference, we showed that TomoSAR has the potential to retrieve the top-of-canopy height with an error to within 2.5 m. Our analyses show that the TomoSAR-AGB retrieval method is accurate even in hilly and high-biomass forest areas and suggest that our approach may be generalizable to other study sites, having a canopy taller than 30 m. These results have strong implications for the tomographic phase of the BIOMASS spaceborne mission. (c) 2016 Elsevier Inc All rights reserved.

【 授权许可】

Free