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Research article - Peer-reviewed, 2021

Assessing Forest Type and Tree Species Classification Using Sentinel-1 C-Band SAR Data in Southern Sweden

Udali, Alberto; Lingua, Emanuele; Persson, Henrik J.;

Abstract

The multitemporal acquisition of images from the Sentinel-1 satellites allows continuous monitoring of a forest. This study focuses on the use of multitemporal C-band synthetic aperture radar (SAR) data to assess the results for forest type (FTY), between coniferous and deciduous forest, and tree species (SPP) classification. We also investigated the temporal stability through the use of backscatter from multiple seasons and years of acquisition. SAR acquisitions were pre-processed, histogram-matched, smoothed, and temperature-corrected. The normalized average backscatter was extracted for interpreted plots and used to train Random Forest models. The classification results were then validated with field plots. A principal component analysis was tested to reduce the dimensionality of the explanatory variables, which generally improved the results. Overall, the FTY classifications were promising, with higher accuracies (OA of 0.94 and K = 0.86) than the SPP classification (OA of 0.66 and K = 0.54). The use of merely winter images (OA = 0.89) reached, on average, results that were almost as good as those using of images from the entire year. The use of images from a single winter season reached a similar result (OA = 0.87). We conclude that multiple Sentinel-1 images acquired in winter conditions are feasible to classify forest types in a hemi-boreal Swedish forest.

Keywords

SAR; backscatter; forest classification; C-band; Sentinel-1

Published in

Remote Sensing

2021, volume: 13, number: 16, article number: 3237
Publisher: MDPI

Authors' information

Udali, Alberto
University of Padua
Lingua, Emanuele
University of Padua
Swedish University of Agricultural Sciences, Department of Forest Resource Management

Associated SLU-program

Remningstorp

UKÄ Subject classification

Remote Sensing

Publication Identifiers

DOI: https://doi.org/10.3390/rs13163237

URI (permanent link to this page)

https://res.slu.se/id/publ/113468