Discriminating Forest Successional Stages, Forest Degradation, and Land Use in Central Amazon Using ALOS/PALSAR-2 Full-Polarimetric Data
Open Access
- 26 October 2020
- journal article
- research article
- Published by MDPI AG in Remote Sensing
- Vol. 12 (21), 3512
- https://doi.org/10.3390/rs12213512
Abstract
We discriminated different successional forest stages, forest degradation, and land use classes in the Tapajós National Forest (TNF), located in the Central Brazilian Amazon. We used full polarimetric images from ALOS/PALSAR-2 that have not yet been tested for land use and land cover (LULC) classification, neither for forest degradation classification in the TNF. Our specific objectives were: (1) to test the potential of ALOS/PALSAR-2 full polarimetric images to discriminate LULC classes and forest degradation; (2) to determine the optimum subset of attributes to be used in LULC classification and forest degradation studies; and (3) to evaluate the performance of Random Forest (RF) and Support Vector Machine (SVM) supervised classifications to discriminate LULC classes and forest degradation. PALSAR-2 images from 2015 and 2016 were processed to generate Radar Vegetation Index, Canopy Structure Index, Volume Scattering Index, Biomass Index, and Cloude–Pottier, van Zyl, Freeman–Durden, and Yamaguchi polarimetric decompositions. To determine the optimum subset, we used principal component analysis in order to select the best attributes to discriminate the LULC classes and forest degradation, which were classified by RF. Based on the variable importance score, we selected the four first attributes for 2015, alpha, anisotropy, volumetric scattering, and double-bounce, and for 2016, entropy, anisotropy, surface scattering, and biomass index, subsequently classified by SVM. Individual backscattering indexes and polarimetric decompositions were also considered in both RF and SVM classifiers. Yamaguchi decomposition performed by RF presented the best results, with an overall accuracy (OA) of 76.9% and 83.3%, and Kappa index of 0.70 and 0.80 for 2015 and 2016, respectively. The optimum subset classified by RF showed an OA of 75.4% and 79.9%, and Kappa index of 0.68 and 0.76 for 2015 and 2016, respectively. RF exhibited superior performance in relation to SVM in both years. Polarimetric attributes exhibited an adequate capability to discriminate forest degradation and classes of different ecological succession from the ones with less vegetation cover.This publication has 75 references indexed in Scilit:
- Discriminação de incrementos de desflorestamento na Amazônia com dados SAR R99B em banda LActa Amazonica, 2010
- Tropical forests were the primary sources of new agricultural land in the 1980s and 1990sProceedings of the National Academy of Sciences of the United States of America, 2010
- Indigenous Lands, Protected Areas, and Slowing Climate ChangePLoS Biology, 2010
- Modeling the carbon balance of Amazonian rain forests: resolving ecological controls on net ecosystem productivityEcological Monographs, 2009
- Forest loss and fragmentation in the Amazon: implications for wildlife conservationOryx, 2000
- Polarimetric SAR speckle filtering and its implication for classificationIEEE Transactions on Geoscience and Remote Sensing, 1999
- A three-component scattering model for polarimetric SAR dataIEEE Transactions on Geoscience and Remote Sensing, 1998
- A review of target decomposition theorems in radar polarimetryIEEE Transactions on Geoscience and Remote Sensing, 1996
- Support-vector networksMachine Learning, 1995
- Radar remote sensing of forest and wetland ecosystems in the Central American tropicsRemote Sensing of Environment, 1994